So, if a teacher is explaining to a class in Grammar the difference between a noun and verb, the explanation would do as well for several hundred as for the dozen who constitute the class, if arrangements could only be made to have the hundreds hear it; but there are, perhaps, only a hundred pupils in the school, and of these a large part understand already the point to be explained, and another large part are too young to attend to it.

I wish the object of these remarks not to be misunderstood.

I do not recommend the attempt to teach on so extensive a scale; I admit that it is impracticable; I only mean to show in what the impracticability consists, namely, in the difficulty of making such arrangements as to derive the full benefit from the instructions rendered.

The instructions of the teacher are, _in the nature of things,_ available to the extent I have represented, but in actual practice the full benefit can not be derived.

Now, so far as we thus fall short of this full benefit, so far there is, of course, waste; and it is difficult or impossible to make such arrangements as will avoid the waste, in this manner, of a large portion of every effort which the teacher makes.
A very small class instructed by an able teacher is like a factory of a hundred spindles, with a water-wheel of power sufficient for a thousand.
In such a case, even if the owner, from want of capital or any other cause, can not add the other nine hundred, he ought to know how much of his power is in fact unemployed, and make arrangements to bring it into useful exercise as soon as he can.