Ruskin distinguishes between the nature and duties of men and women in Sesame and Lilies. He discusses a man's duties as fitted to his more rugged nature. This makes a man's duties, at least as generally understood, public, while the woman's are private. The man, for example, finds his duty defending and providing for the maintenance of the home, while the woman's duty is inside the home, caring for it.

However, Ruskin makes clear that men have private as well as public duties. The best of men understand their duty is not simply to get ahead in life financially or in terms of status but, more importantly, to become wise through reading great literature and learning the fundamental truths that great writers, like John Milton, can convey.

Ruskin also says a man's duties go beyond defending and financially improving the home that the woman cares for and beautifies. A man also has the duty of defending his country or commonwealth, as well as advancing it. As Ruskin puts it,

The man’s duty as a member of a commonwealth, is to assist in the maintenance, in the advance, in the defence of the state.

A man has, as well, an instinct for what Ruskin calls "real" duties. At the heart of these is love: a man must not allow his natural love to be warped, because this does great harm. For example, the love of power that is part of the nature of a man is not bad per se, but it can, if misused "wreck" the "majesty of law and life."

Ruskin speaks, too, of a man's (which he shares with women) duty to God and focuses on the important duty of building "a beautiful human creature [rather] than a beautiful dome or steeple."

Ruskin's essay is an expression of Victorian notions of manhood and womanhood, and for that reason the work is not much read today, as our ideas of gender roles have changed.