Haig (1921) and Simons (1938). Goode (1977) argues persuasively that von Schanz anticipated the Haig-Simons definition in 1896 and so prefers “Schanz-Haig-Simons”. Non-recurring incomes derive from infrequent or unusual events such as the sale of assets, the settlement of insurance contracts, etc. A capital gain is accrued when the value of the asset increases.