Higher wages are never a cause for higher profits, although they may be one of the consequences of higher profits during some particular phases of the industrial cycle.
 Karl Marx, Das Kapital (1894). copy citation

Context

“The industrial capitalist invests it in means of production and in labour-power. The rising demand for labour-power can never by itself be a cause for a rising rate of interest, in so far as the latter is determined by the rate of profit. Higher wages are never a cause for higher profits, although they may be one of the consequences of higher profits during some particular phases of the industrial cycle. The demand for labour-power can increase because the exploitation of labour takes place under especially favourable circumstances, but the rising demand for labour-power, and thus for variable capital, does not in itself increase the profit;” source