In his first bodybuilding book "Sandow's System of Physical Physical Training", Sandow writes...

"The exercises in Heavy-Weight Lifts, it must be said, chiefly by way of caution, are designed for those only who desire, and have the necessary strength, to become athletes. For ordinary health purposes, and for reducing corpulency or checking the tendency to become fat, the light-weight exercises which preceed those now about to be detailed, will be found sufficent, especially in the case of those who have not robust frames, or whose daily live limits them to confining pursuits."

Sandow clearly says in his text that the light-weight exercise are for the general population to tone and accustom the body to proper exercise, while the heavy-weight exercises build an athletic body. He also says that before one attempts the heavy-weight exercises, the light-weight program should be followed for at least 3 months.