Only Kṛṣṇa, the Supreme Personality of Godhead, is controller over the laws of nature. Therefore, if we take shelter of Kṛṣṇa seriously, there will be no fear of being thrown back into the cycle of so many species of life. A sincere devotee will surely be transferred to the abode of Kṛṣṇa, as affirmed in Bhagavad-gītā.
In the Padma Purāṇa, also, the same process is advised. There it is said that one should always remember Lord Viṣṇu. This is called dhyāna, or meditation—always remembering Kṛṣṇa. It is said that one has to meditate with his mind fixed upon Viṣṇu. Padma Purāṇa recommends that one always fix his mind on the form of Viṣṇu by meditation and not forget Him at any moment. And this state of consciousness is called samādhi, or trance.
We should always try to mold the activities of our lives in such a way that we will constantly remember Viṣṇu, or Kṛṣṇa. That is Kṛṣṇa consciousness. Whether one concentrates his mind on the four-handed form of Viṣṇu or on the form of two-handed Kṛṣṇa, it is the same. The Padma Purāṇa recommends: somehow or other always think of Viṣṇu, without forgetting Him under any circumstances. Actually this is the most basic of all regulative principles. For, when there is an order from a superior about doing something, there is simultaneously a prohibition. When the order is that one should always remember Kṛṣṇa, the prohibition is that one should never forget Him. Within this simple order and prohibition, all regulative principles are found complete.
This regulative principle is applicable to all varṇas and āśramas, the castes and occupations of life. There are four varṇas, namely the brāhmaṇas (priests and intellectuals), the kṣatriyas (warriors and statesmen), the vaiśyas (businessmen and farmers) and the śūdras (laborers and servants). There are also four standard āśramas, namely brahmacarya (student life), gṛhastha (householder), vānaprastha (retired) and sannyāsa (renounced). The regulative principles are not only for the brahmacārīs (celibate students) to follow, but are applicable for all. It doesn't matter whether one is a beginner—a brahmacārī—or is very advanced—a sannyāsī. The principle of remembering the Supreme Personality of Godhead constantly and not forgetting Him at any moment is meant to be followed by everyone without fail.
If this injunction is followed, then all other rules and regulations will automatically fall into line. All other rules and regulations should be treated as assistants or servants to this one basic principle.