"Trade has for centuries been, and still is, part of the national way of life; everyone is supposed to know what "trade" means; so Parliament which wrote it into the income tax in 1799 has wisely abstained from defining it and has left it to the courts to say what it does or does not include… “Trade cannot be precisely defined, but certain characteristics can be identified which trade normally has. Equally some indicia can be found which prevent a profit from being regarded as the profit of a trade. Sometimes the question whether an activity is to be found to be trade becomes a matter of degree, frequency, of organisation, even intention, and in such cases it is for the fact-finding body to decide on the evidence whether a line is passed. ... "