“In estimating, then, the causes of the variations in the value of commodities, although it would be wrong wholly to omit the consideration of the effect produced by a rise or fall of labour[71] it would be equally incorrect to attach much importance to it; and consequently, in the subsequent part of this work, though I shall occasionally refer to this cause of variation, I shall consider all the great variations which take place in the relative value of commodities to be produced by the greater or less quantity of labour which may be required from time to time to produce them.”[72] This citation from the _Principles_, edition of 1821, indicates the position Ricardo usually took. But occasionally he appears to have wavered regarding the proper emphasis of the qualification. For instance, in 1820 he wrote: “I sometimes think that if I were to write the chapter on value again which is in my book, I should acknowledge that the relative value of commodities was regulated by two causes instead of by one, namely, by the relative quantity of labour necessary to produce the commodities in question _and by the rate of profit_”....[73] Ricardo’s theory of value, as qualified by himself, might be summarized: Objects of utility, “produced by labor” (the function of factors in production other than labor not explained), and capable of further production by the application of more labor, have normal values in proportion to the total quantity of labor required to produce them, except that this proportionality is disturbed “by the employment with labor of capital of various degrees of durability.”