Where does “res ipsa loquitur” come from?

res ipsa loquitur (English) comes from Latin res ipsa loquitur, from Latin ipsa, from Latin ipse, from Proto-Italic *e(s)peso.

Ancestry of “res ipsa loquitur”, step by step

Step	Language	Word	Meaning
1	Latin	res ipsa loquitur	the thing speaks for itself
2	Latin	ipsa	nominative feminine singular of ipse; nominative...
3	Latin	ipse	himself, herself, itself, the very, the actual;...
4	Proto-Italic	*e(s)peso	—