The city has no need of sun or moon, for the glory of God illuminates the city, and the Lamb is its light. (Revelation NLT)
Light is not a mental thing: that is to say, it is not just a matter of having a store of mental knowledge. That is not light. It is possible to have an enormous amount of doctrine and truth and never be luminaries, that is, never register impact upon darkness. Real light is experimental: that is to say, it is the fruit of experience, the experience of suffering. How have you children of God come to know what you do know of the Lord, that real kind of knowledge of the Lord which is so precious to us, which means so much and which makes you in that measure of value to others? It is through suffering, it is through the difficult way the Lord has led you, it is through the work of the Cross that He has wrought in you. “The Lamb is the lamp” – suffering leading to knowledge, to light, to understanding. It is the only way. These people at the end will be in the good of a great and wonderful revelation which has come by their fellowship with Christ in His sufferings. It is very true. It may not be too comforting from one standpoint, but it is true; and it ought to help us to realize this: that the Lord, in the way in which He is dealing with us, in the sufferings which He allows to come upon us, is really seeking our education, that we may have a knowledge of Himself which can only come that way, and which is a peculiar kind of knowledge of tremendous value to us and through us to others. We do not learn in any other way. It is the Lamb, always the Lamb-principle, the way of suffering and sacrifice and self-emptying, that brings us into the knowledge of the Lord. “The Lamb is the lamp thereof”; and, just as it is deeper death unto fuller life, so it may often be deeper darkness unto fuller light.
The Lord seems to lead us in a way where we are less and less able naturally to understand Him. He gets us altogether out of our natural capacity, beyond our capacity for interpreting His ways. We just do not know what the Lord is doing, or why He is doing what He is doing; yet it is the way by which we come to a very real kind of inward knowledge of Himself. It may not be capable of explanation in words to anybody, but we know, somehow or other we know, and that is a mighty thing, a mighty power of knowledge. It is light through the Cross.