The authors of the following offer an introduction to symmetry
in quilt blocks. They assume, perhaps rightly, that their audience
is intellectually impaired:
“A quilt block is made of 16 smaller squares.
Each small square consists of two triangles.”
Study this example of definition.
(It applies quite precisely to the sorts of square patterns
discussed in the 1976 monograph Diamond Theory , but
has little relevance for quilt blocks in general.)
Some background for those who are not intellectually impaired:
Robinson’s book Definition , in this journal and at Amazon.