LADY CHATTERLEY'S LOVER, by D.H. Lawrence (1928)
Probably the most famous sexually explicit novel of all time, it looks a little tame by some standards today.

''He laid his hand on her shoulder, and softly, gently, it began to travel down the curve of her back, blindly, with a blind stroking motion, to the curve of her crouching loins. And there his hand softly, softly, stroked the curve of her flank, in the blind instinctive caress.''