Joy by Peter Kreeft
Freud says that spiritual joy is a substitute for physical pleasure. People become saints out of sexual frustrations.
This is exactly the opposite of the truth. St. Thomas Aquinas says, "No man can live without joy. That is why one deprived of spiritual joy goes over to carnal pleasures." Sanctity is never a substitute for sex, but sex is often a substitute for sanctity.
The simplest, most unanswerable proof that Aquinas is right and Freud is wrong, is experience. It is not a matter of faith alone. It has been proved by experience by many, many people, many, many times. You can repeat the experiment and prove it to yourself. You can be absolutely certain that it is true, just as you can be certain that fire is hot and ice is cold.
Millions of people for thousands of years have tried the experiment, and not one of them has ever been cheated. All who seek, find—this is not just a promise about the next life, to be believed by faith, but a promise about this life, to be proved by experience, to be tested by experiment.
No one who ever said to God, "Thy will be done" and meant it with his heart, ever failed to find joy—not just in heaven, or even down the road in the future in this world, but in this world at that very moment, here and now. ~Peter Kreeft, Joy