Bereishit Rabbah 9:7
And God saw all that God had made, and found it very good. And there was evening and there was morning, the sixth day.” Nahman said in R. Samuel’s name: “Very good” refers to the Good Desire [Yeitzer Hatov]; and “very good” refers to the Evil Desire [Yeitzer Hara]. Can then the Evil Desire be very good? That would be extraordinary! But without the Evil Desire, however, one would not build a house, marry, beget children, or engage in business.
Zohar Hadash, Bereshit 11a-11b
“You shall sanctify yourselves and you shall be holy (Lev. 11:44). This teaches that one should sanctify oneself during intercourse. What is the relevance of sanctification here? Rabbi Judah ben Jacob said: It means that one should not act licentiously or obscenely, or with whorish intentions like animals, for this is how animals act.
Shmuley Boteach, Dating Secrets of the 10 Commandments, p189
Judaism insists on a holistic approach to human love and sexuality whereby they are one and the same and cannot be separated. Carnal love must be accompanied by heartfelt love, and attraction to the body must engender attraction to the soul.
Art Green - a Contemporary approach to Jewish sexuality
[There is] for the Jew an ideal of sexuality. While we know well that most human sexuality hardly approaches this exalted pictures, it does provide us with a point of view. It indicates strongly that we Jews should stand opposed to the current moves toward the "the demystificication" of sexuality, which seeks to define coupling as purely biological function. We are made most fully human by the fact that this act, shared by us with the animal kingdom, can be raised in our consciousness to the rung of the raza de-yihuda - the sublime mystery of union, Sexuality at its fullest is brimming with religious kavanah [intention]: this is a teaching we would be fools to ignore. If we cannot fulfill the ideal, we can begin to approach it.