I assert not that wherever the word is preached, the good effects of it immediately appear; but that it is never received so as to obtain a permanent establishment, except in order that it may be efficacious. However this may be, where the word is heard with reverence, and the sacraments are not neglected, there we discover, while that is the case, an appearance of the Church, which is liable to no suspicion or uncertainty, of which no one can safely despise the authority, or reject the admonitions, or resist the counsels, or slight the censures, much less separate from it and break up its unity. - Calvin's Institutes Book 4 Chapter 1Unity, unity, unity. But what I really love in this short quote is an admission that results (good fruit) are not proof of faithfulness.
We (as fallen-judgmental man) so wish God's approval would be revealed in tangible success. We as ministers wish we could judge our work in the same way a businessman judges his — numbers.
God's ways (often to our frustration) are higher than ours.
And unrelated but worth mentioning due to recent um, labeling, I should note that not all who read Calvin (or quote him for that matter) are followers thereof.