Eleazar of Worms, Sefer ha-Roqeah, § 20, p. 30

Jewish Mysticism
I should not restrain my spirit for the sake of my Creator for even a short while, and I should not take pleasure for even a short while in matters of adultery and impurity. I must accustom my eyes to [not] look at the face of a woman for she is fire….Everyone looks at the face of women, but he does not and this is the worship of the Creator in truth. One must avoid all physical pleasure with women, seeing them, touching them, sitting with them, seeing their lovely garments, hearing their voices in speech or song, speaking with them, whether married or single, with the exception of his wife.

Translated by Elliot Wolfson in “The Face of Jacob in the Moon- Mystical Transformations of an Aggadic Myth,” in The Seduction of Myth in Judaism- Challenge and Response, 235-270. Edited by S. Daniel Breslauer. Albany- State University of New York Press, 1997.