To be happy in old age, it is necessary that we accustom ourselves to objects that can accompany the mind all the way through life, and that we take the rest as good in their day. The mere man of pleasure is miserable in old age, and the mere drudge in business is but a little better; whereas, natural philosophy, mathematical and mechanical science, are a continual source of tranquil pleasure, and in spite of the gloomy dogmas of priests and of superstition, the study of these things is the true theology; it teaches man to know and to admire the creator, for the principles of science are in the creation, and are unchangeable and of divine origin.