The side of competition which happens for the moment to be weaker is also the side in which the individual acts independently of, and often directly against, the mass of his competitors, and precisely in this manner is the dependence of one upon the other impressed upon them, while the stronger side acts always more or less as a united whole against its antagonist.
 Karl Marx, Das Kapital (1894). copy citation

Context

“The sums react on one another as units, as aggregate forces. The individual counts here only as part of a social force, as an atom of the mass, and it is in this form that competition brings out the socialcharacter of production and consumption. The side of competition which happens for the moment to be weaker is also the side in which the individual acts independently of, and often directly against, the mass of his competitors, and precisely in this manner is the dependence of one upon the other impressed upon them, while the stronger side acts always more or less as a united whole against its antagonist. If the demand for this particular kind of commodity is greater than the supply, one buyer outbids another — within certain limits — and so raises the price of the commodity for all of them above the market-value, while on the other hand the sellers unite in trying to sell at a high market-price.” source