Full Idea
The concept of twelve is in no way already thought by merely thinking the unification of seven and five, and though I analyse my concept of such a possible sum as long as I please, I shall never find twelve in it.
Gist of Idea
7+5 = 12 is not analytic, because no analysis of 7+5 will reveal the concept of 12
Source
Immanuel Kant (Prolegomena to Any Future Metaphysic [1781], 269)
Book Reference
Kant,Immanuel: 'Prolegomena to Any Future Metaphysic', ed/tr. Lucas,Peter G. [Manchester UP 1971], p.19
A Reaction
It might be more plausible to claim that an analysis of 12 would reveal the concept of 7+5. Doesn't the concept of two collections of objects contain the concept of their combined cardinality?
Related Ideas
Idea 16926 Analytic judgements say clearly what was in the concept of the subject [Kant]
Idea 16927 Analytic judgement rests on contradiction, since the predicate cannot be denied of the subject [Kant]