Remark 2.2.2.6. Let $M$ be a monoid, which we view as a (strict) monoidal category having only identity morphisms. Then the $2$-category $BM$ of Example 2.2.2.5 can be identified with the ordinary category $BM$ appearing in Remark 1.3.2.4.

$\Newextarrow{\xhookrightarrow}{10,10}{0x21AA}$