Enough fragments of Euripides' lost tragedy, Bellerophon, remain embedded as some thirty quotations in surviving texts to give scholars a basis for assessing its theme: the tragic outcome of his attempt to storm Olympus on Pegasus. An outspoken passage—in which Bellerophon seems to doubt the gods' existence from the contrast between the wicked and impious, who live lives of ease, with the privations suffered by the good—is apparently the basis for Aristophanes' imputation of atheism to the poet.