Difference between Gashmius and Ruchnius
Rav Yehudah Leib Ashlag, the Ba'al Hasulam, once said "What's the difference between Gashmius (physical pleasures) and Ruchnius (spiritual pleasures)? Gashmius everyone wants, but once you have it, there is no feeling of fulfillment. Ruchniyus on the other hand, nobody wants, but when you have it, there is such a deep feeling of fulfillment!"
How true this is with the pursuit of sexual pleasures. The whole world is running after it, almost everything in the media revolves around the "desire" for it. But you'll seldom, if ever, hear someone talk about how good he feels after it's over. It's all "want, want want" with no fulfillment. Spirituality on the other hand, no one seems to want. But someone who has it, there's no need to ask him how enlightened and uplifted his life feels!