That Christ should manifest Himself to them, and yet be invisible to the world, was a mystery to the disciples. They could not understand the words of Christ in their spiritual sense. They were thinking of the outward, visible manifestation. They could not take in the fact that they could have the presence of Christ with them, and yet He be unseen by the world. They did not understand the meaning of a spiritual manifestation. { SW September 13, 1898, par. 2 }