When he to whom a person speaks does not understand, and he who speaks does not understand himself, that is metaphysics.

When he that speaks, and he to whom he speaks, neither of them understand what is meant, that is metaphysics

Four thousand volumes of metaphysics will not teach us what the soul is

When he to whom one speaks does not understand, and he who speaks himself does not understand, that is metaphysics.

Quand celui à qui l'on parle ne comprend pas et celui qui parle ne se comprend pas, c'est de la métaphysique

When he to whom a person speaks does not understand, and he who speaks does not understand himself, that is metaphysics.

He avoided the metaphysics of the ancients and shunned the unanchored speculations of academics. Not one to be guided by loose medical theorizing, he turned to data based on observations and careful experiments.