Be a philosopher; but, amidst all your philosophy, be still a man. - David Hume

Nay, if we should suppose, what seldom happens, that a popular religion were found, in which it was expressly declared that nothing but morality could gain the divine favor; if an order of priests were instituted to inculcate this opinion in daily sermons and with all the arts of persuasion; yet so inveterate are the people's prejudices, that, for want of some other superstition, they would make the very attendance on these sermons the essentials of religion, rather than place them in virtue and good morals.

[T]he Old Testament, [...] if considered as a general rule of conduct, would lead to consequences destructive of all principles of humanity and morality.

At present they [philosophers] seem to be in a very lamentable condition, and such as the poets have given us but a faint notion of in their descriptions of the punishment of Sisyphus and Tantalus. For what can be imagin'd more tormenting, than to seek with eagerness, what for ever flies us; and seek for it in a place, where 'tis impossible it can ever exist?