The Ten Lepers. There are, speaking broadly, three chief reasons for unthankfulness on the part of man towards God
I. An indistinct idea or an under-estimate of the service that He renders us.
II. A disposition, whether voluntary or not, to lose sight of our Benefactor.
III. The notion that it does not matter much to Him whether we acknowledge His benefits or not.
Gratitude is our bounden duty, because it is the acknowledgment of a hard fact the fact that all things come of God; the fact that we are utterly dependent upon Him; the fact that all existence, all life, is but an overflow of His love; because to blink this fact is to fall back into the darkness and to forfeit that strength which comes always and everywhere with the energetic acknowledgment of truth. Morally speaking, the nine lepers were not the men they would have been if, at the cost of some trouble, they had accompanied the one who, "when he saw that he was healed, turned back, and with a loud voice glorified God... giving Him thanks."
H. P. Liddon, Penny Pulpit,No. 455.
References: Luke 17:15-19. Spurgeon, Sermons,vol. xxxii., No. 1935.Luke 17:17. Homilist,3rd series, vol. ii., p. 161.Luke 17:17; Luke 17:18. C. Kingsley, Town and Country Sermons,p. 375; Homilist,vol. vii., p. 207.