Our thought bursts through the battlements of heaven, and is not satisfied with knowing only what is shown to us: “I investigate,” it says, “that which lies without the world, whether it be a bottomless abyss, or whether it also is confined within boundaries of its own: what the appearance of the things outside may be, whether they be shapeless and vague, extending equally in every direction, or whether they also are arranged in a certain kind of order: whether they are connected with this world of ours, or are widely separated from it and welter about in empty space: whether they consist of distinct atoms, of which everything that is and that is to be, is made, or whether their substance is uninterrupted and all of it capable of change: whether the elements are naturally opposed to one another, or whether they are not at variance, but work towards the same end by different means.” Since man was born for such speculations as these, consider how short a time he has been given for them, even supposing that he makes good his claims to the whole of it, allows no part of it to be wrested from him through good nature, or to slip away from him through carelessness; though he watches over all his hours with most miserly care, though he live to the extreme confines of human existence, and though misfortune