For example, the diagonal going up and to the left from C i…

For example, the diagonal going up and to the left from C in the diagram forms a division of the octave in three major thirds: C-Ab-E-C (the E is actually an Fb, and the final C a Dbb).
https://twetch.app/t/ca8f1bd1c3e7b45aae4c125057896ae84f9fa27a6895ce4bb9fe960d59eebbbe