Material bondage is caused by putting oneself under the control of matter because of the false ego of lording it over material nature. Bhagavad-gītā (BG 7.27) states, icchā-dveṣa-samutthena. Two kinds of propensities arise in the living entity. One propensity is icchā, which means desire to lord it over material nature or to be as great as the Supreme Lord. Everyone desires to be the greatest personality in this material world. Dveṣa means "envy." When one becomes envious of Kṛṣṇa, or the Supreme Personality of Godhead, one thinks, "Why should Kṛṣṇa be the all and all? I'm as good as Kṛṣṇa." These two items, desire to be the Lord and envy of the Lord, are the beginning cause of material bondage. As long as a philosopher, salvationist or voidist has some desire to be supreme, to be everything, or to deny the existence of God, the cause remains, and there is no question of his liberation.
Devahūti very intelligently says, "One may theoretically analyze and say that by knowledge he has become freed, but actually, as long as the cause exists, he is not free." Bhagavad-gītā confirms that after performing such speculative activities for many, many births, when one actually comes to his real consciousness and surrenders unto the Supreme Lord, Kṛṣṇa, then the fulfillment of his research in knowledge is actually achieved. There is a gulf of difference between theoretical freedom and actual freedom from material bondage. The Bhāgavatam (10.14.4) says that if one gives up the auspicious path of devotional service and simply tries to know things by speculation, one wastes his valuable time (kliśyanti ye kevala-bodha-labdhaye). The result of such a labor of love is simply labor; there is no other result. The labor of speculation is ended only by exhaustion. The example is given that there is no benefit in husking the skin of an empty paddy; the rice is already gone. Similarly, simply by the speculative process one cannot be freed from material bondage, for the cause still exists. One has to nullify the cause, and then the effect will be nullified. This is explained by the Supreme Personality of Godhead in the following verses.