Very early in the history of Greek philosophy, happiness became the center of keen speculation and the science of ethics had its origin in these theories.
According to Socrates, happiness consists in the cultivation of the mind and must not be built on the perishable things of the external world.
The Cyrenaics and the Stoics, assuming happiness to be the result of following nature, diverged to opposite poles.
The former claimed that felicity signified gratification of the senses which are the voices of nature; the latter advocated the satisfaction of reason by the entire suppression of the lower appetites.
Plato and Aristotle rejected these two extreme views and both agreed in considering happiness as the highest good.
Plato defines it as that harmonious functioning of the parts of man's soul which shall preserve the subordination of the lower to the higher faculties.
Aristotle was distinctly human in concerning himself with the happiness which it is possible for man to gain in this life, a felicity which springs from the highest virtue.
He asserts that there are two virtues: the ethical or practical attainable by the majority, which does not exclude wealth, pleasure, friends, etc., and the intellectual or speculative which is acquired by the exercise of the best faculties and which only a few philosophers may achieve.
It remained for Christian philosophers to go beyond the present life.
Saint Thomas taught that happiness, the supreme end of man, is open to all but is unattainable in this life.
It consists in the exercise or activity of man's highest faculties, the intellect and the will, in the contemplation and possession of the one object of infinite worth, God, and inconsequent felicity of the lower powers so that the whole of man's complex nature may enjoy perfect beatitude.
Relative and incomplete happiness in this world may be obtained by self-restraint, detachment, and sacrifice of transitory enjoyment for the sake of the eternal end.
Since Descartes, philosophy has been separated from theology and the problem of modern thought is temporal happiness which is identified with pleasure.
Some stress the difference between higher and lower pleasures, between active and passive pleasures, between pleasures that endure and those that pall by repetition.
John Stuart Mill and others, departing somewhat from these hedonistic principles, adopted a theory of utilitarianism which teaches altruism and the happiness of the community.
Finally, the extremists degenerate into pessimism declaring that human misery outweighs happiness and that supreme felicity is altogether impossible.
New Catholic Dictionary