By 1930, Lipchitz began to introduce more overt themes and human content into his sculpture, bringing to an end what he called his "Olympian period" of formal exploration and hermetic content. Sharp contours, smooth surfaces, and geometric patterns gave way to naturalistic anatomies expressively distorted, strongly modeled surfaces, and broken, irregular contours. Tragic, violent, and ecstatic themes in subjects of mythological or religious origin predominated. Birth of the Muses grew out of a series of small sketches from 1944 treating the theme of Pegasus. According to myth, this winged horse alighted on Mt. Olympus. Where its four hooves touched the ground, four springs of water emerged in which the muses were born. In its allusion to the birth of inspiration it also relates to Lipchitz's autobiography as he felt a surge of renewed creative energy in New York after escaping war-torn France in 1941. In Lipchitz's first maquette, Pegasus was shown frontally. The artist turned him in profile and developed the sculpture in a high relief that is nonetheless fully finished in the round. While expressing minor reservations about the somewhat square contours of the piece, Lipchitz felt it was particularly important and identified it as the germ of his subsequent monumental Bellerophon Taming Pegasus.