12. Use has ever been made of comparisons taken from the pleasures of the senses when these are mingled with that which borders on pain, to prove that there is something of like nature in intellectual pleasures. A little acid, sharpness or bitterness is often more pleasing than sugar; shadows enhance colours; and even a dissonance in the right place gives relief to harmony. We wish to be terrified by rope-dancers on the point of falling and we wish that tragedies shall well-nigh cause us to weep. Do men relish health enough, or thank God enough for it, without having ever been sick? And is it not most often necessary that a little evil render the good more discernible, that is to say, greater? 13. But it will be said that evils are great and many in number in comparison with the good: that is erroneous. It is only want of attention that diminishes our good, and this attention must be given to us through some admixture of evils. If we were usually sick and seldom in good health, we should be wonderfully sensible of that great good and we should be less sensible of our evils. But is it not better, notwithstanding, that health should be usual and sickness the exception? Let us then by our reflexion supply what is lacking in our perception, in order to make the good of health more discernible. Had we not the knowledge of the life to come, I believe there would be few persons who, being at the point of death, were not content to take up life again, on condition of passing through the same amount of good and evil, provided always that it were not the same kind: one would be content with variety, without requiring a better condition than that wherein one had been. 14. When one considers also the fragility of the human body, one looks in wonder at the wisdom and the goodness of the Author of Nature, who has made the body so enduring and its condition so tolerable. That has often made me say that I am not astonished men are sometimes sick, but that I am astonished they are sick so little and not always. This also ought to make us the more esteem the divine contrivance of the mechanism of animals, whose Author has made machines so fragile and so subject to corruption[131] and yet so capable of maintaining themselves: for it is Nature which cures us rather than medicine. Now this very fragility is a consequence of the nature of things, unless we are to will that this kind of creature, reasoning and clothed in flesh and bones, be not in the world. But that, to all appearance, would be a defect which some philosophers of old would have called _vacuum formarum_, a gap in the order of species.