“The lender either gives credit to the borrower or transfers to him certain rights of obtaining credit which had previously belonged to the lender, and this supply of credit is the service which the lender performs for the borrower, in return for which the borrower pays him interest. Consequently this provision of credit is the originating cause or source of the interest received by the lender. Although, colloquially, one speaks of a debt carrying interest, or interest on a debt, as though interest were a sort of growth sprouting from the debt, the language used means no more than that the borrower pays interest, if that is the agreement between borrower and lender, as consideration for the benefits allowed to him by the lender” (ibid., 10). Davis, A.J.A., in agreement with Watermeyer. C.J., said: “The practical man would say that the source of Levers’ income was the provision by it of assets in America and the giving of credit in England” (ibid., 23). Schreiner J.A., disagreed, his view being that when income is derived by a person from another who is using that person’s property, and that property happens to be money, the interest is derived from the loan, the local situation of which must be ascertained. I think the decision of the majority is to be preferred. It appears to me that in interpreting s. 87 (n), proper regard must be paid to the word “derived”; it should not be read as “received”
"Source means not a legal concept, but something which a practical man would regard as a real source of income"; "the ascertaining of the actual source is a practical hard matter of fact."