Darwin's ideas developed rapidly from the return in 1836 of the "Beagle" survey expedition. By December 1838 he had developed the principles of his theory. At that time similar ideas brought others disgrace and association with the revolutionary mob. He was conscious of the need to answer all likely objections before publishing. While he continued with research as his "prime hobby", his priority was an immense amount of work on geology and analysing and publishing findings from the "Beagle" expedition. This was repeatedly delayed by illness.