There is, no doubt, a double idea in the metaphor which the Psalmist employs. He desires to set forth, by his image of a shadow, not only the transiency, but the unsubstantialness of life. Shadow is opposed to substance, to that which is real, as well as to that which is enduring. And we may further say that the one of these characteristics is in great part the occasion of the other. Because life is fleeting, therefore, in part, it is so hollow and unsatisfying. The fact that men are dragged away from their pursuits so inexorably makes these pursuits seem, to any one who cannot see beyond that fact, trivial and not worth the following. Why should we fret and toil and break our hearts,' and scorn delights, and live laborious days' for purposes which will last so short a time, and things which we shall so soon have to leave? What is all our bustle and business, when the sad light of that thought falls on it, butlabouring for the wind'? Were it not better to lie still?' Such thoughts have at least a partial truth in them, and are difficult to meet as long as we think only of the facts and results of man's life that we can see with our eyes, and our psalm gives emphatic utterance to them. The word rendered walketh' in our text is not merely a synonym for passing through life, but has a very striking meaning. It is an intensive frequentative form of the word--that is, it represents the action as being repeated over and over again. For instance, it might be used to describe the restless motion of a wild beast in a cage, raging from side to side, never still, and never getting any farther for all the racing backward and forward. So here it signifies walketh to and fro,' and implies hurry and bustle, continuous effort, habitual unrest. It thus comes to be parallel with the stronger words which follow,--Surely they are disquieted in vain'; and one reason why all this effort and agitation are purposeless and sad, is because the man who is straining his nerves and wearying his legs is but a shadow in regard to duration--He heapeth up riches, and knoweth not who shall gather them.'
Yes! if we have said all, when we have said that men pass as a fleeting shadow--if my life has no roots in the Eternal, nor any consciousness of a life that does not pass, and a light that never perishes, if it is derived from, directed to, cribbed, cabined, and confined' within this visible diurnal sphere, then it is all flat and unprofitable, an illusion while it seems to last, and all its pursuits are folly, its hopes dreams, its substances vapours, its years a lie. For, if life be thus short, I who live it am conscious of, and possess whether I be conscious of them or no, capacities and requirements which, though they were to be annihilated to-morrow, could be satisfied while they lasted by nothing short of the absolute ideal, the all-perfect, the infinite--or, to put away abstractions, My soul thirsteth for God, the living God!' He hath put eternity in their heart,' as the book of Ecclesiastes says. Longings and aspirations, weaknesses and woes, the limits of creature helps and loves, the disproportion between us and the objects around us--all these facts of familiar experience do witness, alike by blank misgivings and by bright hopes, by many disappointments and by indestructible expectations surviving them all, that nothing which has a date, a beginning, or an end, can fill our souls or give us rest. Can you fill up the swamps of the Mississippi with any cartloads of faggots you can fling in? Can you fill your souls with anything which belongs to this fleeting life? Has a flying shadow an appreciable thickness, or will a million of them pressed together occupy a space in your empty, hungry heart?
And so, dear brethren! I come to you with a message which may sound gloomy, and beseech you to give heed to it. No matter how you may get on in the world--though you may fulfil every dream with which you began in your youth--you will certainly find that without Christ for your Brother and Saviour, God for your Friend, and heaven for your hope, life, with all its fulness, is empty. It lasts long, too long as it sometimes seems for work, too long for hope, too long for endurance; long enough to let love die, and joys wither and fade, and companions drop away, but without God and Christ, you will find it but as a watch in the night.' At no moment through the long weary years will it satisfy your whole being; and when the weary years are all past, they will seem to have been but as one troubled moment breaking the eternal silence. At every point so profitless, and all the points making so thin and short a line! The crested waves seem heaped together as they recede from the eye till they reach the horizon, where miles of storm are seen but as a line of spray. So when a man looks back upon his life, if it have been a godless one, be sure of this, that he will have a dark and cheerless retrospect over a tossing waste, with a white rim of wandering barren foam vexed by tempest, and then, if not before, he will sadly learn how he has been living amidst shadows, and, with a nature that needs God; has wasted himself upon the world. O life I as futile then as frail'; surely,' in such a case,' every man walketh in a vain show.'