"All the formulæ of Conic Sections having long since gone out of my head, I went on my return to London to the Royal Institution to read them up. Professor, now Sir James Dewar, came in and probably noticing signs of despair in my face, asked me what I was about; then said, "Why do you bother over this? My brother in law, J. Hamilton Dickson of Peterhouse, loves problems and wants new ones. Send it to him." I did so... and he most cordially helped me by working it out... on the basis of the... Gaussian Law of Error."