The author - the dean of Moscow University psychological department - addresses the students. Ho underlines the dual nature of psychology - it produces the new information and, on the other hand, it consists of certain actions. Scientific research and psychological practice require different sorts of professionals. The main functions of a psychologist directed to society benefit are stated. Basic principles of scientific discussions are considered. There are some indisputable scientific authorities (they are listed) to be leaned upon to overcome arising contradictions (which are however necessary for scientific development).