But this may come later; and it may be the burden of another great moment of revelation. For, as I have hinted already in this lecture, the true Christian life is not all a silent, unmarked growth; it has its crises also, when it rises at a bound to new levels, where new prospects unfold themselves before it and alter everything. There are moments in life more precious than days, and there are days which we would not exchange for years. Swept along with other materials into the common receptacle of memory, they shine like gold, silver, precious stones among the wood, hay, stubble of ordinary experience. It is impossible to say how much one such experience may do to direct and to inspire a life. I believe that many a humble minister has such an experience hidden in his memory, which he may never have disclosed to anyone, but which is invested for himself with unfading splendor and authority, and binds him to the service of God till his dying day.[12] But this principle, which we have drawn for our own use from Isaiah's call, applies not only to the initial act, but to every subsequent detail of our life. It is true of every appearance which a minister makes before a congregation. Unless he has spent the week with God and received Divine communications, it would be better not to enter the pulpit or open his mouth on Sunday at all. There ought to be on the spirit, and even on the face of a minister, as he comes forth before men, a ray of the glory which was seen on the face of Moses when he came down among the people with God's message from the mount.