The theme of the 'Birth of Venus' by Botticelli?

Sandro Botticelli. Answer 2: I am sure the above is the answer you wanted, since Botticelli's painting is the best-known version of 'Birth of Venus'. One should know, though, that this has been a very popular subject thorugh the ages and painted by many famous and less famous painters.
Boticelli
Sandro Botticelli, painted circa 1482-1486.