"The signs won't look as you expect them to look"

"Here on the mountain, the air is clear and your mind is clear; as you drop down into Narnia, the air will thicken. Take great care that it does not confuse your mind. The signs which you have learned will not look at all as you expect them to look, when you meet them there. That is why it is so important to know them by heart and pay no attention to appearances”
-Aslan in C.S. Lewis, The Silver Chair, 25-26).
Thanks, Tia