who came up with the doctrine of signatures
Doctrine of signatures Paracelsus (1493–1541) developed the concept, writing that "Nature marks each growth ... according to its curative benefit",[1] and it was followed by Giambattista della Porta in his Phytognomonica (1588).
Key signature Put another way: for key signatures with sharps, the first sharp is placed on F with subsequent sharps on C, G, D, A, E and B; for key signatures with flats, the first flat is placed on B with subsequent flats on E, A, D, G, C and F. There are thus 15 conventional key signatures, with up to seven sharps or flats and including the empty signature of C major (A minor).