Abstract
Goldbach’s conjecture, if not read in number theory, but in a precise foundation theory of mathematics, that refers to the metaphysical ‘theory of the participation’ of Thomas Aquinas, poses a surprising analogy between the category of the quantity, within which the same arithmetic conjecture is formulated, and the transcendental/formal dimension. It says: every even number is ‘like’ a two, that is: it has the form-of-two. And that means: it is the composition of two units; not two equal arithmetic units, but two different formal-transcendental units, which are, in arithmetic, two prime numbers.