Not once in the entire endless series of lives was there a real birth. There was only the appearance of birth.

There was never a real death, only a change in appearance, similar to the transition from sleep to wakefulness...

... throughout the endless succession of lives, there was never any real experience of transitioning from one state to another or any real experience of being in any other place.

This is similar to images in a dream.

Longchenpa

"In Buddhist noscriptures, this original nature is principally referred to as “mind” (sems), as in “ever-perfect mind” (kun tu bzang po’i sems) or “mind nature” (sems nyid ). In this context, “mind” does not mean object-bound experience but instead the ever-perfect and intrinsic awareness that has no beginning or end. Since it is free from the dichotomy of knower and known, this mind is no different from the reality it perceives.

Reality is a “continuum” in the sense that its nature does not change into something else and cannot be fragmented into parts. Regardless of the degree of evolution or debasement of an individual, that reality or ever-perfect mind remains unaltered as the very essence or nucleus of one’s being.

From the state of an ordinary individual, the beginning, so to speak, up to the end of awakening, such reality is unceasingly present. Hence, there is no ultimate distinction between an ordinary being and an awakened one."

Elio Guarisco

"Continuum as actuality (rang bzhin), though deemed causal (rgyu), does not mean the presence of the original state of being as a mere potential to be actualized in the future. Actuality points to the full presence of original being, even when it is not recognized. Lack of recognition is like a veil or cloud of unawareness which, however thick, does not pollute the very nature of one’s original state. As explained by the Third Karmapa Rangjung Dorjé, actuality means “an awakened being attended by stains.” Although accompanied by impurity, the being remains the same, just as a gold statue wrapped in rags is still a gold statue."

Elio Guarisco

"Actuality is not defined as an absolute and static emptiness. Its power of manifestation or “radiance” (mdangs), owing to unawareness of its nature and to emotional patterns related to unawareness, becomes the basis for the particular appearances or visions that seem to bind one. When the veils of unawareness and emotional patterns lessen to some extent, there arise pure visions and contemplative experiences reflecting the essential purity of the actuality.

When unawareness and emotional patterns are fully recognized as the mere play of the manifesting power of reality, the entire breadth of the potential of one’s being unfolds."

Elio Guarisco

"As long as the state of enlightenment is not recognized, beings continue to experience illusory birth and death, along with the happiness and suffering inherent in conditioned existence. However, whatever the experience, the essence of enlightenment remains unpolluted, unobscured, and unmodified, just as sunlight maintains its nature of light regardless of the type of object it strikes.

The essence is not conditioned by any form of embodied life, whether fortunate or miserable, nor is it conditioned by any act, good or evil, or by knowledge or lack of knowledge. Although the essence is attended by impurity, its nature, like gold embedded in ore, remains always pure, untouched by emotional afflictions and conceptions."

Elio Guarisco

[T]hrough turning away from the linguistic fabrications of what is seen, heard, perceived, and spoken in the world, mastery over what is seen, heard, perceived, and spoken is attained.

— Vasubandhu

“All the rivers in the world, carrying the waters that ripen flowers and fruit and cause forests to thrive, flow due to the power of the Naga King who resides in Lake Madröpa. Similarly any explanation, debate, composition, practice, and attainment of fruition achieved by his retinue of disciples depends solely on the power of the Victorious One himself.”

Sūtrasamuccaya

“All the lokas must be regarded as planes of consciousness which are attainable... in the physical body.

In effect while still on earth we can raise ourselves to the plane of our choice and will inevitably re-manifest there when the term of earthly existence is ended. But any law, to be a true universal principle, must operate both ways; we cannot logically expect the cosmic law to work only in our favour. If it did, there would be no point in man’s freedom of choice in moral issues. Where it is open to man to go upward, forward, it must be open to him to descend in the scale of spiritual evolution also.

Greed, hatred, sensuality and inertia all have their appropriate spheres of manifestation and their corresponding corporeal forms. When these types of consciousness arise more frequently than their spiritual opposites of generosity, love, purity and energy, they create the form of the next birth.”

Francis Story

“A Guru should never sell mantra-knowledge to a disciple. A Guru who sells mantra is sinful and surely goes to hell.

Mantra-dīkṣā is to be given only through generosity and grace. One whose mind is tainted by greed is not a Guru and cannot uplift a disciple.

Whoever gives dīkṣā out of desire for wealth takes the wrong path. For such a person, no siddhi of the mantra arises; the practice becomes fruitless.”

Kulārṇava Tantra 13.108–110

Regarding the practice of Mantra & Tantra without the guidance of a Guru:

"Pustake likhitā vidyā yena sundari yapyate
Sidhir na jāyate tasya kalpakoti-ṣaṭair api.

O Beauteous one! He who does Japa of a Vidyā [Mantra] learnt from a book can never attain Siddhi even if he persists for countless millions of years."

Ṣaṭkarmadīpikā

“How, then, are the two vehicles differentiated? Some say that the difference between Sūtra and Mantra is that Mantra was taught for those who can use desire as an aid in the path whereas the Perfection Vehicle was taught in order to tame beings within the context of separation from desire.

This opinion is wrong because both the Perfection Vehicle and the Mantra Vehicle have modes of advancing on the path without having abandoned desire and both have modes of progress by cultivating paths to abandon desire.

For, in Sūtra it is said that just as the filth of a city is helpful to the field of a sugarcane grower who knows how to utilize a substance which itself is not helpful, so the afflictions can be useful in the path. If one knows how to use the afflictions for the welfare of others, they can serve as aids in amassing the accumulations of merit, and in this sense desire is not one-pointedly to be avoided although, from the viewpoint of the entities of the afflictions, they are indeed to be abandoned.

Sūtra Bodhisattvas who have not yet thoroughly abandoned the afflictions of desire and hatred can use them for the benefit of others, as in the case of Bodhisattva kings who have fathered many children in order to further the welfare of the country through the work of their children. Here the afflictions act as secondary causes in the aiding of others.

Just as within Sūtra practice there are occasions when Bodhisattvas intentionally do not abandon afflictions but use them as aids, so in Mantra practice, according to the time and the situation, Bodhisattvas use the afflictions. However, on the occasions when there is no purpose for desire or hatred, a Mantra practitioner must intentionally seek to abandon them. If in order to be a practitioner of Mantra one necessarily had to have not abandoned desire and hatred, there would be no opportunity to become a Buddha through the Mantra path.”

Tenzin Gyatso, 14th Dalai Lama