In thinking ahead towards the future, it is often useful to look back to find what factors have allowed us to reach our present state of knowledge. In my life as a scientist, three factors have been important. One of these factors has been CHANCE, and I will illustrate its influence on my development of a new way of separating proteins by sharing with you my laboratory notebook entries from over 50 years ago. Curiosity is also a prime mover in science. And so, out of curiosity, I tested my new protein separation method with blood plasma. The tests in due course led to the discovery of complicated genetic differences between the plasma proteins of different persons. At this stage, the second factor came into play. There was now an OPPORTUNITY to disentangle these complex new findings. The solution to this genetic problem pointed to the frequent occurrence of homologous recombination in biology. The third factor, PLANNING, had the most important consequences – I was able to devise a plan to alter genes in living cells by homologous recombination (gene targeting). The subsequent extension of this idea to altering genes in animals has been hugely successful. The message for the future that comes from this backwards look is that we must make sure that your generation of scientists will also have the freedom to take advantage of scientific chances. We must also make sure that you have the opportunity to develop your findings in ways that improve human welfare. But, above all, you must enjoy doing what you do. For without that you will never be able to look back, as I can, at 60 years of enjoyable science.