Chris Aldrich’s Reviews > Abstract and Concrete Categories: The Joy of Cats > Status Update

Some initial discussion of sets, classes, and conglomerates to keep us out of trouble with some of the potential foundational issues that can be found in set theory.

"Therefore we advise the beginner to skip from here, go directly to§3, and return to this section only when the need arises."

They've buried the lede of the section here apparently.