“The soul is self-moved. That which is self-moved is perpetually moved. That which is perpetually moved is immortal. The soul, therefore, is immortal. … By motion here, we must understand the life of the soul. The soul therefore is self-vital, containing in itself the principle and fountain of motion.”

Syllogism from Hermeas’ commentary on Plato’s Phaedrus 245c - 245e.

"Sin should be abstained from, not through fear, but for the sake of the becoming."

The Golden Sentences of Democrates 7

Plotinus, Ennead 5.9.3, on how to perceive the intellectual nature of reality and how this relates to soul:

It is better to ask if intellect is such as we say it is, and if it is something separate, and if this is identical with Being and if the nature of Forms is here. Regarding this, it remains for the following to be said.

We certainly see that all things that are said to be are composites not one of which is simple, both whatever craft fashions and whatever is constituted by nature. For the products of craft are just bronze or wood or stone, and nothing is made from them until a particular craft fashions a statue or a bed or a house, introducing the form which it has in itself.

Further, the same goes for the things constituted by nature, some of which are multiply composited and are called compounds; these can be analysed into the form and the compounded elements that it governs. For example, a human being can be analysed into soul and body, and the body into the four elements. And when you find that each of these is composite of matter and something that shapes it - for matter by itself is without shape - you will investigate where the form comes to matter from. You will investigate, again, whether the soul is among the simples already or whether there is something in it that is composed of matter and form; and whether the intellect in it has one part which is like the shape in the bronze and another part which is like the one who produces the shape in the bronze.

And, then transferring these considerations onto the whole universe, one will ascend to posit Intellect, too, as the true producer or creator, and one will say that the substrate, having received shapes, becomes fire, water, air, and earth. These shapes come from another. This is the soul; it is soul, again, that gives to the four elements the shape of the cosmos. But it is Intellect that supplies the expressed principles for this to be generated, just as the expressed principle comes from the crafts to the souls of the craftsmen to actualize. Intellect is, then, the form of the soul, analogous to the shape, and that which provides the shape is analogous to one who produced the statue, in whom everything which he imposed, pre-existed. That which Intellect gives to the soul is near to the truth; what the body receives are already images and imitations.

To summarise the reasons that made them [i.e., people like Socrates] adopt the hypothesis of Ideas, let us say that all visible things, both heavenly and sublunary, exist either by chance or by a cause. But that it should be by chance is impossible, for in that case superiors and inferiors will be classed together—intellect, reason-principle, and cause along with things derived from causes—and thus products will be superior to principles. Besides, as Aristotle says, essential causes must be prior to accidental ones, for the accidental cause is a by-product of essential causes—so that what comes about causally would be prior to the accidental if even the divinest parts of the visible world have come about by accident. And if there are causes of all things, they will be either many and unconnected, or one. But if they are many, we shall be unable to say what makes the universe one; and yet the one is superior to the many, and the whole to the parts. But if there is one cause of the unitary universe with respect to which all things are ordered, it will be absurd if this cause is without reason; for again there will be something superior to the universal cause among its effects, viz. whatever being acts according to reason and knowledge, which will be within the All and a part of it and be the kind of thing it is from an irrational cause. But if this cause has reason and knows itself, it obviously knows itself as the cause of all things; otherwise, being ignorant of this, it would be ignorant of its own nature. And if it knows that it is by its own essence the cause of the All, it knows also the effect of which it is the cause. For what knows the cause determinately, necessarily knows also the effect. Therefore it knows also determinately the effect which it causes. Consequently it knows both the All and everything of which the All consists and of which it is also the cause. And if this is true, it is by looking to itself and knowing itself that it knows what comes after it. Hence it is by immaterial reason-principles and forms that it knows the reason principles in the cosmos and the Ideas of which the All consists; and the All is in it as in a cause separate from Matter.

Proclus, Commentary on the Parmenides 799

Epictetus, Discourses chapter 2

And surely a self-controlled person would do what's appropriate with respect to both gods and human beings. For if he does what's inappropriate, he wouldn't be self-controlled. And of course if he did what's appropriate with respect to human beings, he would be doing what's just, and with respect to gods he would be doing what's pious, and one who does what's just and pious must necessarily be just and pious.

Plato, Gorgias 507b

Explore the River of the Soul, so that although you have
become a servant to body, you may again rise
to the Order from which you descended, joining works to sacred reason.

The Chaldean Oracles

"The supervisor of the universe has arranged everything with an eye to its preservation and excellence, and its individual parts play appropriate active or passive roles according to their various capacities. These parts, down to the smallest details of their active and passive functions, have each been put under the control of ruling powers that have perfected the minutest constituents of the universe. Now then, you perverse fellow, one such part - a mere speck that nevertheless constantly contributes to the good of the whole - is you, you who have forgotten that nothing is created except to provide the entire universe with a life of prosperity. You forget that creation is not for your benefit: you exist for the sake of the universe. Every doctor, you see, and every skilled craftsman always works for the sake of some end-product as a whole; he handles his materials so that they will give the best results in general, and makes the parts contribute to the good of the whole, not vice versa."

Plato, Laws 903b-d

All beings are beings due to unity, both those beings that are primarily Beings and those that are said to be among beings in any way. For what could be, if it were not a unity?

Plotinus, Ennead 6.9.1

Therefore good people won’t be willing to rule for the sake of either money or honor. They don’t want to be paid wages openly for ruling and get called hired hands, nor to take them in secret from their rule and be called thieves. And they won’t rule for the sake of honor, because they aren’t ambitious honor-lovers. So, if they’re to be willing to rule, some compulsion or punishment must be brought to bear on them - perhaps that’s why it is thought shameful to seek to rule before one is compelled to. Now, the greatest punishment, if one isn’t willing to rule, is to be ruled by someone worse than oneself. And I think that it’s fear of this that makes decent people rule when they do. …It would be quite clear that anyone who is really a true ruler doesn’t by nature seek his own advantage but that of his subject.

Plato, Republic 347b-d

"It is our task as founders, then, to compel the best natures to reach the study we said before is the most important, namely, to make the ascent and see the Good. But when they’ve made it and looked sufficiently, we mustn’t allow them to do what they’re allowed to do today."

"What’s that?"

"To stay and refuse to go down again to the prisoners in the cave and share their labors and honors, whether they are of less worth or greater."

"Then are we to do them an injustice by making them live a worse life when they could live a better one?"

"You are forgetting again that it isn’t the law’s concern to make any one class in the city outstandingly happy but to contrive to spread happiness throughout the city by bringing the citizens into harmony with each other through persuasion or compulsion and by making them share with each other the benefits that each class can confer on the community. The law produces such people in the city, not in order to allow them to turn in whatever direction they want, but to make use of them to bind the city together."

Plato, Republic 519c-520a

Since, then, there is soul that engages in calculative reasoning about just and beautiful things, that is, calculative reasoning that seeks to know if this is just or if this is beautiful, it is necessary that there exists permanently something that is just, from which the calculative reasoning in the soul arises. How else could it engage in calculative reasonings? And if soul sometimes engages in calculative reasoning about these things and sometimes does not, there must be Intellect that does not engage in calculative reasoning, but always possesses Justice, and there must be also the principle of Intellect and its cause and god. And it must be indivisible and unchanging; and while not changing place, it is seen in each of the many things that can receive it, in a way, as something other. Just as the centre of the circle exists in its own right, but each of the points on the circle contains it in itself, the radii add their unique character to it. For it is by something like this in ourselves that we are in contact with the One and are with it and depend on it. And if we converge on it, we would be settled in the intelligible world.

Plotinus, Enneads 5.1.11

But these powers [of rationality], beginning from the lowest, are opinion, dianoia, and the summit of dianoia, which summit is the intellect of the human soul, and is that power, by the light of which we perceive the truth of axioms, it being intuitive perception. Dianoia is the discursive energy of reason; or it is that power which reasons scientifically, deriving the principles of its reasoning from intellect. And opinion is that power which knows that a thing is, but is ignorant of the cause of it, or why it is.

From a footnote by Thomas Taylor to Porphyry’s Auxiliaries to the Perception of Intelligible Natures

The deification, however, of dead men, and the worshipping men as Gods, formed no part of this theology, when it is considered according to its genuine purity. Numerous instances of the truth of this might be adduced, but I shall mention for this purpose, as unexceptionable witnesses, the writings of Plato, the Golden Pythagoric Verses, and the Treatise of Plutarch on Isis and Osiris. All the works of Plato, indeed, evince the truth of this position, but this is particularly manifest from his Laws. The Golden verses order that the immortal Gods be honoured first, as they are disposed by law; afterwards the illustrious Heroes, under which appellation the author of the verses comprehends also angels and daemons, properly so called; and in the last place, the terrestrial daemons, i.e. such good men as transcend in virtue the rest of mankind. But to honour the Gods as they are disposed by law, is, as Hierocles observes, to reverence them as they are arranged by their demiurgus and father; and this is to honour them as beings not only superior to man, but also to daemons and angels. Hence, to honour men, however excellent they may be, as Gods, is not to honour the Gods according to the rank in which they are placed by their Creator; for it is confounding the divine with the human nature, and is thus acting directly contrary to the Pythagoric precept. Plutarch too, in his above mentioned treatise, most forcibly and clearly shows the impiety of worshipping men as Gods.

Thomas Taylor, Introduction to Iamblichus' On the Mysteries

The philosophers say that the first thing that needs to be learned is the following, that there is a God, and a God who exercises providential care for the universe, and that it is impossible to conceal from him not only our actions, but even our thoughts and intentions. The next thing to be considered is what the gods are like; for whatever they’re discovered to be, one who wishes to please and obey them must try to resemble them as far as possible. If the deity is trustworthy, he too must be trustworthy; if free, he too must be free; if beneficent, he too must be beneficent; if magnanimous, he too must be magnanimous. And so thenceforth, in all that he says and does, he must act in imitation of God.

Epictetus, Discourses 2.14.11-13

According to Iamblichus, rites and sacrifices are not mere human customs but are ruled over by divinities, and every nation and people has its own guardian.

"If, therefore, these were human customs alone, and derived their authority through our legal institutions, it might be said that the worship of the Gods was the invention of our conceptions. Now, however, divinity is the leader of it, who is thus invoked by sacrifices, and who is surrounded by a numerous multitude of Gods and angels. Under him, likewise, a certain common presiding power, is allotted dominion according to each nation of the earth. And a peculiar presiding power is allotted to each temple. Of the sacrifices, also, which are performed to the Gods, the inspective guardian is a God; but an angel, of those which are performed to angels; and a daemon, of such as are performed to daemons."

Iamblichus, On the Mysteries 236-237

Some key concepts of this tradition. Not an exhaustive list.

1. Gods are really existent; they are not mere archetypes or metaphors.
2. The Gods are good.
3. The cosmos we inhabit is as good as it possibly could be and is, in Plato’s words, a “shrine to the Gods.” The universe is a theophany.
4. The Gods and other beings actively maintain and order the cosmos, which is an expression of divine goodness, power, and intelligence. “Everything is full of Gods.”
5. The cardinal virtues are Justice, Wisdom, Courage, and Temperance.
6. We are to become as like to the Gods as we can, and this is in essence what it means to be virtuous. We must align ourselves with “that which always is” rather than with “that which is always becoming.”
7. Your soul is immortal.

Perhaps as a legacy of Christianity, we tend to have a dualistic perspective that sees the divine realm as separated off from and apart from the cosmos, but this is not the orthodox Platonic position. Rather the cosmos is a direct expression of the divine and is, so to speak, infused with divinity; and it is this fact that allows for ritual communication.