His aspiration for social justice and a (relatively) egalitarian society, as well as his desire to refine the religious practices and beliefs of his contemporaries.
My favorite thing about Muhammed [pbuh] is that he was commanded to "Read" three times by the Archangel Gabriel. Muhammed never learned to read. What's up with that?
Mohammed's encounter with the angel was inspiring, in light of his illiteracy. What I love most about him is public speaking, creating a society of equals, fostering inter-faith understanding (peacefully co-existing with Christians, Jews, Animists, and others). And who could forget his teachings.