Discussions of it can be found on the Web. It is so well known by now that if there were an Academy of Computation in Athens, it would surely be carved on the lintel. I have the impression that when Hamming himself was asked to explain what he meant, he wiggled around and came up with changing interpretations and constant modifications. These quotations all call for discussion, and some have indeed been discussed ever since the Greeks invented philosophy. The last two, for example, when properly interpreted, may come as close to expressing social concern as Hamming was able to bring himself to do publicly.
Regeneration is increasingly easier than retrieval.
Now here is a thought that diffuses rapidly into the related but separate questions of research strategies, of originality, plagiarism, rights of intellectual property, royalties. Not so many years after my PhD was awarded, I was working alongside old Professor PDQ, a mathematician of great international reputation. As a graduate student, I had relied on my thesis adviser to certify the originality of my results. But now I was on my own, and for a few days I trembled in my boots. On study, it turned out that while my theorem and Professor PDQ's were located in the same specific area of mathematics, my hypotheses as well as the methods I employed were quite different.