Many people do it, and fall into great mistakes thereby,--mistakes that even a little child, if it would think, need not commit.

But really great philosophers sometimes make this mistake about Why and How; and therefore it is no wonder if other people make it too, when they write children's books about the wonders of nature, and call them "Why and Because," or "The Reason Why." The books are very good books, and you should read and study them: but they do not tell you really "Why and Because," but only "How and So." They do not tell you the "Reason Why" things happen, but only "The Way in which they happen." However, I must not blame these good folks, for I have made the same mistake myself often, and may do it again: but all the more shame to me.
For see--you know perfectly the difference between How and Why, when you are talking about yourself.

If I ask you, "Why did we go out to-day ?" You would not answer, "Because we opened the door." That is the answer to "How did we go out ?" The answer to Why did we go out is, "Because we chose to take a walk." Now when we talk about other things beside ourselves, we must remember this same difference between How and Why.

If I ask you, "Why does fire burn you ?" you would answer, I suppose, being a little boy, "Because it is hot;" which is all you know about it.

But if you were a great chemist, instead of a little boy, you would be apt to answer me, I am afraid, "Fire burns because the vibratory motion of the molecules of the heated substance communicates itself to the molecules of my skin, and so destroys their tissue;" which is, I dare say, quite true: but it only tells us how fire burns, the way or means by which it burns; it does not tell us the reason why it burns.
But you will ask, "If that is not the reason why fire burns, what is ?" My dear child, I do not know.