The approaches of different authors to the determination of the purpose of science are discussed in this work. Author considers definitions of science based on different values. Author explores the correlation between science and value of control over natural objects, as well as cognitive values. Groups of cognitive values available in the literature are given as examples. The definition of science based on the understanding that science is unique complex self-organizing system is suggested. The historical aspect of the problem of (...) motivation scientific activity is considered. Attention to one of the most important values associated with science, the ability to ensure control over nature, is attracted. The provision that the motivation of scientific activity is not related to the value of control over natural objects is proved. It is shown that the leading motivation of the man of science - the need for knowledge of nature. This requirement is a manifestation of the evolutionary mechanism of survival of the species Homo Sapiens. (shrink)