How well would be, if men would but exercise their brains as they do their bodies, and take as much pain for virtue as they do for pleasure
I thought but emphasize the verb...Is it right? And if it is right, how it can be paraphrased?
"But" here means "merely", as in, if people would just take this small step.
A long-winded paraphrase would be, "If men would just take the simple, easy step of exercising their brains ..."