1. The Petrarchan conceit, used in love poetry, exploits a particular set of images for comparisons with the despairing lover and his unpitying but idolized mistress. For instance, the lover is a ship on a stormy sea, and his mistress "a cloud of dark disdain"; or else the lady is a sun whose beauty and virtue shine on her lover from a distance.
The paradoxical pain and pleasure of lovesickness is often described using oxymoron, for instance uniting peace and war, burning and freezing, and so forth. But images which were novel in the sonnets of Petrarch became clichˇs in the poetry of later imitators. Romeo uses hackneyed Petrarchan conceits in describing his love for Rosaline as "bright smoke, cold fire, sick health"; and Shakespeare parodies such conceits in Sonnet 130: "My mistress' eyes are nothing like the sun."
2. The metaphysical conceit is characteristic of seventeenth-century writers influenced by John Donne, and became popular again in this century after the revival of the metaphysical poets. This type of conceit draws upon a wide range of knowledge, from the commonplace to the esoteric, and its comparisons are elaborately rationalized.
For instance, Donne's "The Flea" (1633), partially quoted above, compares a flea bite to the act of love; and in "A Valediction: Forbidding Mourning" (1633) separated lovers are likened to the legs of a compass, the leg drawing the circle eventually returning home to "the fixed foot."