Contrary to general opinion concerning the "pessimistic" "skeptical" and even "nihilistic" philosophy of Ecclesiastes, the author, analyzing text, comes to the conclusion that the author of this biblical book appears to be quite optimistic in crucial aspects of this reflection and in his final conclusion in point of the righteous ones requital anyway beyond the grave, if not terrestrial; it is this belief that fills (must fill) all their life and activity with meaningfulness and importance. Ecclesiastes appreciates rather positively the possibilities of human cognition-it is a perpetual comprehension process of permanently varying world. The author adduces numerous relevant biblical parallels to the corresponding Ecclesiastes' thesis in his study. Ht also advances some arguments for the idea that Ecclesiastes could be composed by the Yudaean governor Zerubbabel (the end of thee VI century BC), who was a descendant of King David.