French medicine was of the utmost importance for the birth of modern medicine and neurology in the 19th century. Innovative approaches, such as examination at the bedside, the use of the stethoscope, techniques of auscultation, palpation, and close patient examination, besides emphasis on anatomical-clinical correlation and observation of the outcome of the disease, were put into practice. Fren...

This was discovered by Euler in the 18th century, forgotten, and then rediscovered in the 19th century by Hamilton in his work on quaternions. Shortly after Hamilton’s rediscovery of (1.2) Cayley discovered a similar 8-square identity. In all of these sum-of-squares identities, the terms being squared on the right side are all bilinear expressions in the x’s and y’s: each such expression, like ...