Assuming that the knowledge is kept constant.revisit
“The law of returns states that with the quantity of complementary factors held constant, there always exists some optimum amount of the varying factor. The law that such an optimum must exist can be proved by contemplating the implications of the contrary.” (p. 35)
“According to the law of returns, there is an optimum of proportions of factors, given other factors, in the production of any given product. We shall see that our analysis of factor pricing is based only on this praxeological law and not on more restrictive technological assumptions.” (pp. 455-456)