Stuck? Go daydream!

That's what August Kekulé did when he was trying to figure out molecular structures, including the benzene ring, in the mid-1800s. In one:

Long lines often fitted together more densely; everything in motion, twisting and turning like snakes. But look, what was that? One of the snakes had seized its own tail, and the figure whirled mockingly before my eyes. I awoke as by a stroke of lightning, and this time, too, I spent the rest of the night working out the consequences of the hypothesis.

And that's how the idea of the benzene ring was born.

https://www.nature.com/articles/465036