@ChelanJim Here’s a screenshot of a few pages from one of my favorite books.
"Hypercubes
ADDENDUM
HIRAM BARTON, a consulting engineer of Etchingham, Sussex, England, had the following grim comments to make about Hin- ton’s colored cubes:
DEAR MR. GARDNER:
A shudder ran down my spine when I read your reference to Hinton’s cubes. I nearly got hooked on them myself in the nine- teen-twenties. Please believe me when I say that they are com- pletely mind-destroying. The only person I ever met who had worked with them seriously was Francis Sedlak, a Czech neo- Hegelian philosopher (he wrote a book called The Creation of Heaven and Earth) who lived in an Oneida-like community near Stroud, in Gloucestershire.
As you must know, the technique consists essentially in the sequential visualizing of the adjoint internal faces of the poly- colored unit cubes making up the large cube. It is not difficult to acquire considerable facility in this, but the process is one of autohypnosis and, after a while, the sequences begin to parade themselves through one’s mind of their own accord. This is pleasurable, in a way, and it was not until I went to see Sedlak in 1929 that I realized the dangers of setting up an autonomous process in one’s own brain. For the record, the way out is to establish consciously a countersystem differing from the first in that the core cube shows different colored faces, but withdrawal
is slow and I wouldn’t recommend anyone to play around with the cubes at all."