For Spirits when they please Can either sex assume, or both; so soft And uncompounded is their essence pure, Not tied or manacled with joint or limb, Nor founded on the brittle strength of bones, Like cumbrous flesh; but in what shape they choose Dilated or condensed, bright or obscure, Can execute their airy purposes, And works of love or enmity fulfil.

Milton's Poetical Works (ed. 1831)