i couldnt find the exact translation that goldstein quotes in the book, but here's the translation from marxists.org:

We have thus seen that even the most favorable situation for the working class, namely, the most rapid growth of capital, however much it may improve the material life of the worker, does not abolish the antagonism between his interests and the interests of the capitalist. Profit and wages remain as before, in inverse proportion.

If capital grows rapidly, wages may rise, but the profit of capital rises disproportionately faster. The material position of the worker has improved, but at the cost of his social position. The social chasm that separates him from the capitalist has widened.

Finally, to say that "the most favorable condition for wage-labour is the fastest possible growth of productive capital", is the same as to say: the quicker the working class multiplies and augments the power inimical to it – the wealth of another which lords over that class – the more favorable will be the conditions under which it will be permitted to toil anew at the multiplication of bourgeois wealth, at the enlargement of the power of capital, content thus to forge for itself the golden chains by which the bourgeoisie drags it in its train.