But to the attainment of this purpose, the complete supremacy of Reason is indispensable; in order that we may take a right comparative measure of the varieties of pleasure and pain, and pursue the course that promises the least amount of suffering.[12] In all ethical theories that make happiness the supreme object of pursuit, the position of virtue depends entirely upon the theory of what constitutes happiness.

Now, Epicurus (herein differing from the Stoics, as well as Aristotle), did not recognize Happiness as anything but freedom from pain and enjoyment of pleasure.

It is essential, however, to understand, how Epicurus conceived pleasure and pain, and what is the Epicurean scale of pleasures and pains, graduated as objects of reasonable desire or aversion?
It is a great error to suppose that, in making pleasure the standard of virtue, Epicurus had in view that elaborate and studied gratification of the sensual appetites that we associate with the word _Epicurean_.

Epicurus declares--'When we say that pleasure is the end of life, we do not mean the pleasures of the debauchee or the sensualist, as some from ignorance or from malignity represent, but freedom of the body from pain, and of the soul from anxiety.

For it is not continuous drinkings and revellings, nor the society of women, nor rare viands, and other luxuries of the table, that constitute a pleasant life, but sober contemplation, such as searches out the grounds of choice and avoidance, and banishes those chimeras that harass the mind.
Freedom from pain is thus made the primary element of happiness; a one-sided view, respected in the doctrine of Locke, that it is not the idea of future good, but the present greatest uneasiness that most strongly affects the will.