One may argue that the Vedic activities are based on sacrificial ceremonies. That is true. But all such sacrifices are also meant for realizing the truth about Vāsudeva. Another name of Vāsudeva is Yajña (sacrifice), and in the Bhagavad-gītā it is clearly stated that all sacrifices and all activities are to be conducted for the satisfaction of Yajña, or Viṣṇu, the Personality of Godhead. This is the case also with the yoga systems. Yoga means to get into touch with the Supreme Lord. The process, however, includes several bodily features such as āsana, dhyāna, prāṇāyāma and meditation, and all of them are meant for concentrating upon the localized aspect of Vāsudeva represented as Paramātmā. Paramātmā realization is but partial realization of Vāsudeva, and if one is successful in that attempt, one realizes Vāsudeva in full. But by ill luck most yogīs are stranded by the powers of mysticism achieved through the bodily process. Ill-fated yogīs are given a chance in the next birth by being placed in the families of good learned brāhmaṇas or in the families of rich merchants in order to execute the unfinished task of Vāsudeva realization. If such fortunate brāhmaṇas and sons of rich men properly utilize the chance, they can easily realize Vāsudeva by good association with saintly persons. Unfortunately, such preferred persons are captivated again by material wealth and honor, and thus they practically forget the aim of life.
This is also so for the culture of knowledge. According to Bhagavad-gītā there are eighteen items in culturing knowledge. By such culture of knowledge one becomes gradually prideless, devoid of vanity, nonviolent, forbearing, simple, devoted to the great spiritual master, and self-controlled. By culture of knowledge one becomes unattached to hearth and home and becomes conscious of the miseries due to death, birth, old age and disease. And all culture of knowledge culminates in devotional service to the Personality of Godhead, Vāsudeva. Therefore, Vāsudeva is the ultimate aim in culturing all different branches of knowledge. Culture of knowledge leading one to the transcendental plane of meeting Vāsudeva is real knowledge. Physical knowledge in its various branches is condemned in the Bhagavad-gītā as ajñāna, or the opposite of real knowledge. The ultimate aim of physical knowledge is to satisfy the senses, which means prolongation of the term of material existence and thereby continuance of the threefold miseries. So prolonging the miserable life of material existence is nescience. But the same physical knowledge leading to the way of spiritual understanding helps one to end the miserable life of physical existence and to begin the life of spiritual existence on the plane of Vāsudeva.
The same applies to all kinds of austerities. Tapasya means voluntary acceptance of bodily pains to achieve some higher end of life. Rāvaṇa and Hiraṇyakaśipu underwent a severe type of bodily torture to achieve the end of sense gratification. Sometimes modern politicians also undergo severe types of austerities to achieve some political end. This is not actually tapasya. One should accept voluntary bodily inconvenience for the sake of knowing Vāsudeva because that is the way of real austerities. Otherwise all forms of austerities are classified as modes of passion and ignorance. passion and ignorance cannot end the miseries of life. Only the mode of goodness can mitigate the threefold miseries of life. Vasudeva and Devakī, the so-called father and mother of Lord Kṛṣṇa, underwent penances to get Vāsudeva as their son. Lord Śrī Kṛṣṇa is the father of all living beings (BG 14.4). Therefore He is the original living being of all other living beings. He is the original eternal enjoyer amongst all other enjoyers. Therefore no one can be His begetting father, as the ignorant may think. Lord Śrī Kṛṣṇa agreed to become the son of Vasudeva and Devakī upon being pleased with their severe austerities. Therefore if any austerities have to be done, they must be done to achieve the end of knowledge, Vāsudeva.