All living entities within the material creation are conditioned by material nature because of their forgetfulness of their relationship to Viṣṇu, or Kṛṣṇa, the Supreme Personality of Godhead.
(Bhagavad-Gita----3:10----purport).

Actually the living entity is originally the spiritual part and parcel of the Supreme Lord, but due to his rebellious nature, he is conditioned within material nature.
(Bhagavad-Gita----13:20----purport).

All the revealed scriptures are prepared by the Lord through His incarnation in the body of Śrīla Vyāsadeva just to remind the fallen souls, conditioned by material nature, of Śrī Kṛṣṇa, the Personality of Godhead.
(Srimad Bhagavatam----1:2:28:29----purport).

Service is pervertedly represented in the material world and broken untimely, resulting in sad experience. The illusioned living being conditioned by material nature cannot understand out of ignorance that all our relations here in the mundane world are temporary and full of inebrieties.
(Srimad Bhagavatam----1:11:35----purport).

As soon as one always thinks of Kṛṣṇa, he becomes a perfect yogī, as confirmed in Bhagavad-gītā (yoginām api sarveṣāṁ mad-gatenāntarātmanā (BG 6.47)). This antarātmā, the mind, is conditioned by material nature.
(Srimad Bhagavatam----5:11:6----purport).

All the living entities in this material world have come here only because they wanted to be equal to Kṛṣṇa in enjoyment and have thus been sent here to be conditioned by material nature in different degrees.
(Srimad Bhagavatam----7:2:21----purport).

The living entity is born in different families or species of life because of being infected by the modes of material nature. When conditioned by material nature, the living entity must accept a certain type of body, which is offered by nature under the direction of the Supreme Lord.
(Srimad Bhagavatam----7:2:22----purport).

According to this statement from the Prema-vivarta, when a living entity is conditioned by material nature, he is exactly like a person haunted by a ghost.
(Srimad Bhagavatam----7:2:23----purport).

This time factor is the impersonal representation of the Supreme Personality of Godhead, who gives the living entities conditioned by material nature a chance to emerge from this nature by surrendering to Him.
(Srimad Bhagavatam----7:13:6----purport).

There is a great struggle for existence because the living entity conditioned by material nature is under nature's full control.
(Srimad Bhagavatam----9:24:58----purport).

When one conceives of a distinction between His body and His soul, one is immediately conditioned by material nature. Because a person in the material world makes such distinctions, he is called baddha-jīva, a conditioned soul.
(Sri Caitanya Caritamrta----3:5:122----purport).

In the conditioned stage of the living entities, there are two kinds of results of fruitive activities: the conditioned living entity who is constantly engaged in sinful activities has suffering as his result, and he who is engaged in pious activities has material enjoyment as a result. In either case—material suffering or material enjoyment—the sufferer or enjoyer isconditioned by material nature.
(Krsna Book).

Śrī Caitanya Mahāprabhu says that the actual position of the living entity is that of eternal servant of the Supreme Lord. Forgetting this principle, the living entity becomes conditioned by material nature, but in serving the Supreme Lord he becomes the liberated servant of God.
(Bhagavad-Gita----18:73----purport).