There seem to be four circumstances, on which depend all, or the greatest part of the ills, that molest sensible creatures; and it is not impossible but all these circumstances may be necessary and unavoidable.  We know so little beyond common life, or even of common life, that, with regard to the economy of a universe, there is no conjecture, however wild, which may not be just; nor any one, however plausible, which may not be erroneous.  All that belongs to human understanding, in this deep ignorance and obscurity, is to be sceptical, or at least cautious, and not to admit of any hypothesis whatever, much less of any which is supported by no appearance of probability.  Now, this I assert to be the case with regard to all the causes of evil, and the circumstances on which it depends.  None of them appear to human reason in the least degree necessary or unavoidable; nor can we suppose them such, without the utmost license of imagination.

The first circumstance which introduces evil, is that contrivance or economy of the animal creation, by which pains, as well as pleasures, are employed to excite all creatures to action, and make them vigilant in the great work of self-preservation.  Now pleasure alone, in its various degrees, seems to human understanding sufficient for this purpose.  All animals might be constantly in a state of enjoyment:  but when urged by any of the necessities of nature, such as thirst, hunger, weariness; instead of pain, they might feel a diminution of pleasure, by which they might be prompted to seek that object which is necessary to their subsistence.  Men pursue pleasure as eagerly as they avoid pain; at least they might have been so constituted.  It seems, therefore, plainly possible to carry on the business of life without any pain.  Why then is any animal ever rendered susceptible of such a sensation?  If animals can be free from it an hour, they might enjoy a perpetual exemption from it; and it required as particular a contrivance of their organs to produce that feeling, as to endow them with sight, hearing, or any of the senses.  Shall we conjecture, that such a contrivance was necessary, without any appearance of reason? and shall we build on that conjecture as on the most certain truth?

But a capacity of pain would not alone produce pain, were it not for the second circumstance, viz. the conducting of the world by general laws; and this seems nowise necessary to a very perfect Being.  It is true, if everything were conducted by particular volitions, the course of nature would be perpetually broken, and no man could employ his reason in the conduct of life.  But might not other particular volitions remedy this inconvenience?  In short, might not the Deity exterminate all ill, wherever it were to be found; and produce all good, without any preparation, or long progress of causes and effects?