Summary: This paper articulates the idea that the drive to know is the key to sexuality, and that sexuality is the key to subjectivation. It approaches Lacan’s formulae of sexuation starting from the background of Frege’s distinction between function (predicate) and object (argument) on the one hand, and propositional function and quantifier on the other hand. On this basis, the two sides of the Lacanian formulae are interpreted as ‘the all predicative’, le tout prédicat on the one hand, and the courage of the indecision on the other. That a radically escaping point is not without subjective effect, and does make a difference, epistemologically, ontologically and ethically, is what these formulae are seen to illustrate. Where possible, a comparison is being made with Kant’s transcendental philosophy and logics.