Hedonism holds that good and happiness are through sensual gratification, what feels good is good. But, “happiness is an activity of soul in accordance with perfect virtue.” Ethic. i, 13 From which St. Thomas deduces that “man's happiness consists in the knowledge of God, which is an act of the intellect. (Summa, II, I, Q4.4).
Consequently, for perfect happiness the intellect needs to reach the very Essence of the First Cause. And thus it will have its perfection through union with God as with that object, in which alone man's happiness(Summa, II, I,Q4. 8)
A perfect beatitude, perfect happiness, complete well-being, will only be obtained in heaven. Happiness seeks a perfect good, which can only be found in the Perfect God. Thus, a perfect happiness is only found in an objective faith. St. Thomas continues,
Now it has been shown above that Happiness is a good surpassing created nature. Therefore it is impossible that it be bestowed through the action of any creature: but by God alone is man made happy, if we speak of perfect Happiness. If, however, we speak of imperfect happiness, the same is to be said of it as of the virtue, in whose act it consists. (Summa, II, I,Q5.6)
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