And they’ll never be enough:

Trades Unions work well as centres of resistance against the encroachments of capital. They fail partially from an injudicious use of their power. They fail generally from limiting themselves to a guerilla war against the effects of the existing system, instead of simultaneously trying to change it, instead of using their organised forces as a lever for the final emancipation of the working class, that is to say, the ultimate abolition of the wages system.

Karl Marx – Value, Price and Profit (International Publishers p. 62)