A great advantage of X-ray analysis as a method of chemical structure analysis is its power to show some totally unexpected and surprising structure with, at the same time, complete certainty.

Still I had a lurking question. Would it not be better if one could really 'see' whether molecules as complicated as the sterols, or strychnine were just as experiment suggested?

I once wrote a lecture for Manchester University called « Moments of Discovery » in which I said that there are two moments that are important. There's the moment when you know you can find out the answer and that's the period you are sleepless before you know what it is. When you've got it and know what it is, then you can rest easy.

I used to say the evening that I developed the first x-ray photograph I took of insulin in 1935 was the most exciting moment of my life. But the Saturday afternoon in late July 1969, when we realized that the insulin electron density map was interpretable, runs that moment very close.

I first met the subject of X-ray diffraction of crystals in the pages of the book W. H. Bragg wrote for school children in 1925, Concerning the Nature of Things.

I was captured for life by chemistry and by crystals.

I should not like to leave an impression that all structural problems can be settled by X-ray analysis or that all crystal structures are easy to solve. I seem to have spent much more of my life not solving structures than solving them.