Some things can not be done except by bodies; other things can not be well done by them.
 John Stuart Mill, Considerations on Representative Government (1861). copy citation

Context

“and in many cases its control over every thing will be more perfect the less it personally attempts to do. The commander of an army could not direct its movements effectually if he himself fought in the ranks or led an assault. It is the same with bodies of men. Some things can not be done except by bodies; other things can not be well done by them. It is one question, therefore, what a popular assembly should control, another what it should itself do. It should, as we have already seen, control all the operations of government. But, in order to determine through what channel this general control may most expediently be exercised, and what portion of the business of government the representative assembly should hold in its own hands, it is necessary to consider what kinds of business a numerous body is competent to perform properly.” source