Whistler's work can be divided into four periods. The first was a research period in which the artist was influenced by the Realism of Gustave Courbet and by Japanese art. Whistler then discovered his own originality in the Nocturnes and the Cremorne Gardens series, thereby coming into conflict with the academics who wanted a work of art to tell a story. When he painted the portrait of his mother, Whistler entitled it Arrangement in Gray and Black, and this is symbolic of his aesthetic theories.