Charles H. Spurgeon on Psalms 90:12

So teach us to number our days, that we may apply our hearts unto wisdom. Moses who was learned in all the sciences of the Egyptians (among which arithmetic was one) desireth to learn this point of arithmetic only of thee, O Lord; and why? Is it because, as Job speaketh, thou hast determined the number of his days? Would Moses have thee reveal to every man the moment of his end? Such speculations may well beseem an Egyptian, an Israelite they do not beseem. Thy children, O Lord, know that it is not for them so to know times and seasons which thou keepest in thine own power, and are a secret sealed up with thee: we should not pry into that counting house, nor curiously inquire into that sum. It is not then a mathematical numbering of days that Moses would be schooled in, but a moral; he would have God not simply to teach him to number, but to number "so"; and "so" points out a special manner, a manner that may be useful for the children of God. And indeed our petitions must bear this mark of profitable desires, and we should not ask aught of thee but that by which (if we speed) we may become the better; he that so studies his mortality learns it as he should, and it is only thou, O Lord, that takest him out such a lesson. But what is the use, O Moses, that thou wouldst have man make of such a knowledge? "Even to apply his heart unto wisdom." O happy knowledge, by which a man becomes wise; for wisdom is the beauty of a reasonable soul. God created him therewith, but sin hath divorced the soul and wisdom; so that a sinful man is indeed no better than a fool, so the Scripture calleth him; and well it may call him so, seeing all his carriage is vain, and the upshot of his endeavours but vexation of spirit. But though sin have divorced wisdom and the soul, yet are they not so severed but they may be reunited; and nothing is more powerful in furthering this union than this feeling meditation —that we are mortal. —Arthur Lake.