What is Ad Recte Docendum Oportet, Primum Inquirere Nomina, Quia Rerum Cognitio A Nominibus Rerum Dependet?

Legal Definition
In order rightly to comprehend a thing, inquire first into the names, for a right knowledge of things depends upon their names. Co. Litt. 68.
-- Black's Law Dictionary
Legal Definition
For the proper understanding of a thing, it is well first to inquire into the names, because a knowledge of things depends upon their names.
-- Ballentine's Law Dictionary