ab initio -> from the beginning

MSCD 13.376 is quite clear: no latinisms, except the most basic ones - pro rata, status quo, vice versa. Eminently reasonable and in keeping with best practices for readable documents; but reasonable enough that MSCD glosses over it without the usual thorough explanation.

This is a good chance to point out that MSCD's index is excellent and really key to using MSCD well: once you've gone through it once and have internalized the important points, you can use the index every time you're unsure of a specific phrase or concept. Certainly, it is what made this review possible!