NOTE : What is metaphysics? Questionning the being: is it an act inducing knowledge? The etymology of the word metaphysics calls a bit upon the arbitrary fact of it: in the primitive sense, reminds us Lalande, "ta meta ta jusika", name given to Aristoteles's work that we call metaphysics nowadays, because it was the following, in the collection of Aristoteles' works gathered by Andronicus of Rhodos (Ist century BC.), of the jusic akroasixV or Physics. In this form, the expression goes back to the first century of the christian era at the latest; we do not come accross the term metaphysica, in a single word, untill the Middle-Ages, in particular in Averroes' work. In the Middle-Ages, this term was applied to the sofia or filosofia prwth (metaphysics, 1,2,982a4 and following) which subject is the to on h on (Met. III,1,1003a21; V,1,1026a31 etc.) and which is defined by himself as h twn prwtwn akrwn kai aitiwm qewrhtikh (its causes being mainly the tagaqon and the to ou eneka. Ibid- 882b9-10). One would make a comparison with the contemporary approach in Sein und Zeit or in Introduction à la Métaphysique (Gallimard 19..).