Schiller writes in a letter [to Goethe, 17 December 1795] of a ‘poetic mood’. I think I know what he means, I think I am familiar with it myself. It … - Ludwig Wittgenstein

"It is necessary to be given the prop that all elementary props are given." This is not necessary because it is even impossible. There is no such prop! That all elementary props are given is SHOWN by there being none having an elementary sense which is not given.

Getting hold of the difficulty deep down is what is hard. Because if it is grasped near the surface it simply remains the difficulty it was. It has to be pulled out by the roots; and that involves our beginning to think about these things in a new way. The change is as decisive as, for example, that from the alchemical to the chemical way of thinking. The new way of thinking is what is so hard to establish. Once the new way of thinking has been established, the old problems vanish; indeed they become hard to recapture. For they go with our way of expressing ourselves and, if we clothe ourselves in a new form of expression, the old problems are discarded along with the old garment.

The I, the I is what is deeplt mysterious.