"Service of Śrī Kṛṣṇa is the eternal nature of a jīva. When he forgets this relationship he is overwhelmed by the influence of māyā—the deluding potency lying at the background of the Lord. Thenceforward a jīva shows his backwardness in the service of the Supreme Lord Śrī Kṛṣṇa. Since the backward condition of a jīva springs up along with his coming into this māyaik world, the history of his downfall within the bounds of time and space is out of the question. Hence the significance of the expression ‘eternally backward.’ His eternal function with the service of Śrī Kṛṣṇa has been perverted since his entrance into the plane of three dimensions due to his forgetfulness."
(Jīva-dharma, p. 10)

"The root of all actions is the desire for acts, the root of which again is avidyā. Avidyā is the name for the forgetfulness of the reality that ‘I am Kṛṣṇa’s eternal servant.’ This avidyā did not commence within the course of mundane time. That root of karma of the jīva arose when he was at the juncture [between cit and acit regions]. As such, the beginning of karma is not to be traced within mundane time, and, on that account karma is beginningless."
(Jīva-dharma, p. 248)

"The eternal nature of a jīva is the eternal servanthood of Kṛṣṇa. A jīva is the taṭasthā [borderline] potency of Kṛṣṇa and exists simultaneously as a distinct and nondistinct entity. When he forgets Kṛṣṇa he is averse to serve Kṛṣṇa and his aversion has no beginning as it dates before his incarnation within the four walls of time and space."
(Jīva-dharma, p. 8)

"But many cannot understand distinctly how karma has no beginning. Time pertaining to matter is only material reflection of cit-time and is a material thing suited to the performance of karma. Jīva takes recourse to cit i.e. transcendental everlasting time in Vaikuṇṭha, where there is no past and future; only the present exists. When jīva in bondage enters in material time [it] becomes subject to past, future and present and being server of tri-kāla suffers pleasure and pain. Material time originating from cit-kāla and cit-kāla having no beginning, the origin of jīva’s karma i.e. aversion to God is coming even prior to material time. Therefore judged impartially with regard to jaḍa-kāla, the root of karma lies prior to this time and therefore karma has been designated as anādi i.e. without any beginning."
(Śrī Caitanya Śikṣāmṛtam, p. 158)

"Because they are between the internal and external potencies, the eternally transcendental living entities are called the marginal potency of the Lord. Factually, the living entities are not meant to be so conditioned by material energy, but due to their being affected by the false sense of lording it over the material energy, they come under the influence of such potency and thus become conditioned by the three modes of material nature. This external energy of the Lord covers up the pure knowledge of the living entity’s eternally existing with Him, but the covering is so constant that it appears that the conditioned soul is eternally ignorant."
(Śrīmad-Bhāgavatam 2.5.19, purport)

"Similarly, there was no necessity to create this material world for the sufferings of the conditioned souls, but at the same time there are certain living entities, known as nitya-baddha, who are eternally conditioned. We say that they have been conditioned from time immemorial because no one can trace out when the living entity, the part and parcel of the Supreme Lord, became rebellious against the supremacy of the Lord. It is a fact that there are two classes of men... Without tracing out the beginning of the existence of these two classes, we can take it for granted that some of the living entities revolted against the laws of the Lord. Such entities are called conditioned souls... Covered by the material body, the spiritual identity is lost, and therefore the word mumuhe is used here, indicating that they have forgotten their own spiritual identity."
(Bhāg. 3.26.5 purport)

"It is clear that a particular body is given to the living entity for a particular type of activity. This process is going on perpetually, from a time which it is impossible to trace out. Vaiṣṇava poets say, therefore, anādi karama-phale, which means that these actions and reactions of one’s activity cannot be traced, for they may even continue from the last millennium of Brahmā’s birth to the next millennium."
(Śrīmad-Bhāgavatam 3.31.44, significado)

"Eternally conditioned means we do not know when we have been conditioned like this. It is not possible to trace out the history. Because living entity, by nature, he is not conditioned. But actually we see that we are conditioned, and there is no possibility to trace out the history. Many, many Brahmā’s life. Not only one Brahmā’s. There are so many Brahmās changed, and we are conditioned. So therefore we are called eternally conditioned."
(Caitanya-caritāmṛta class, lecture, January 9, 1967, New York)

"So some way or other, originally, we are all Kṛṣṇa conscious, pure, svaccha. Svacchatvam avikāritvam. Now, vikurvāṇāt, now, being transformed or agitated somehow or other... Anādi-karama-phale, padi’ bhavārṇava-jale. We cannot ascertain when this transformation took place... How we fell, you can trace out the history, but it is very difficult because anādi karama phale, nobody can ascertain. Just like when a man is diseased, he goes to doctor... There is no necessity to find out the history how he fell diseased. There is history, but that is not possible to trace out. Therefore it is said, anādi karama-phale. Anādi. Anādi means... Ādi means the creation. Creation... before creation, I [become] contaminated [with] this desire, icchā-dveṣa samutthena."
(Śrīmad-Bhāgavatam, lecture, January 1, 1975, Bombay)

"And there are innumerable spiritual living entities also. And some of them, those who are not fit to live in that spiritual world, they are, I mean to say, sent to this material world. The same idea is expressed in Milton’s Paradise Lost. So we, all conditioned souls, we are practically living in a place after Paradise Lost. We should understand this... Actually we are spirit soul. We should not have accepted this material body. But when we have accepted, how we accepted, there cannot be any tracing of history. It is not possible. Anādi karama. Anādi karama. Nobody can trace out the history, when we, the conditioned soul, accepted this material body."
(Lecture, April 23, 1969, Buffalo, New York)

"Your next question, ‘...We are eternally conditioned, but as soon as we surrender to Krishna do we then become eternally liberated?...’ You are not eternally conditioned. You are eternally liberated but since we have become conditioned on account of our desire to enjoy materialistic way of life, from time immemorial, therefore it appears that we are eternally conditioned. Because we cannot trace out the history or the date when we became conditioned, therefore it is technically called eternally conditioned. Otherwise the living entity is not actually conditioned. A living entity is always pure. But he is prone to be attracted by material enjoyment and as soon as he agrees to place himself in material enjoyment, he becomes conditioned, but that is not permanent."
(Letter to Aniruddha, dated November 14, 1968)