Discoveries—you have to make them yourself. Nobody can do it for you. They can hint, they can suggest this and that, they can ask questions. But ultimately you have to make your own discovery. Something has to click and you should be able to hear it yourself.
Sometimes you can make a discovery and not know it. It is only when you review; when you come across it a second time; that you recognize it to be new and important. Both Christopher Wren and Robert Hook had the suspicion that the force keeping the planets in their elliptical orbits followed an inverse square law. But they did not have the mathematics to prove it. So Edmund Halley took it upon himself to go to Cambridge and ask Newton, the greatest mathematician at the time. Newton’s answer? Yes, the force follows an inverse square law. He had work it out some time ago. Could he show them how it was done? Newton promised he would, provided he could find it among his disorderly collection of papers.
He never found the paper he was looking for. In its place, he took two years to write the Principia in which the same question was answered together with a whole lot of others.
Newton made a major discovery without knowing he had until Halley brought along the suspicion entertained by Wren and Hook! If Halley had not visited Cambridge …
—
Cryptanalytic Method Omnibus Edition: Follow clues and develop new clues from old.
What are clues? Clues are the characteristics of structures, sometimes disguised.
To crack a cipher, you first have to create it. Through trial and error. Guided by clues.