Many artists of historical subjects have used symbolism in their works to convey their perceptions about the subject of their work or the world in which they lived. Symbolism–clothing the idea in perceptible form [Poet Jean Moreas in his 1886 Manifesto of Symbolism]–is a powerful tool in the hands of artists. In order to meaningfully interpret these historical sources, students need to understand symbolism. In addition to symbolism, interpretation is aided by prior knowledge about the subject of the artwork and the historical time period in which it was created.