One of the unique aspects of Friedrich Hayek's life is that his active career covered more than sixty years. Such a lengthy period of intellectual output is virtually unique; some, for example Isaac Newton, approached the same time-span of achievement, but unlike Hayek, Newton outlived his creativity as well as the beneficent effects of his influence. The thrust of this chapter is to discuss changes in Hayek's writings as well as some always existent ideas he came to on his own.