These short and simple answers are all that a child requires.
A full and detailed explanation of any thing they ask about is as tiresome for them to listen to as it is for the mother to frame and give; while a short and simple reply which advances them one step in their knowledge of the subject is perfectly easy for the mother to give, and is, at the same time, all that they wish to receive.
For example, let us suppose that the father and mother are taking a ride on a summer afternoon after a shower, with little Johnny sitting upon the seat between them in the chaise.

The parents are engaged in conversation with each other, we will suppose, and would not like to be interrupted.

Johnny presently spies a rainbow on a cloud in the east, and, after uttering an exclamation of delight, asks his mother what made the rainbow.

She hears the question, and her mind, glancing for a moment at the difficulty of giving an intelligible explanation of so grand a phenomenon to such a child, experiences an obscure sensation of perplexity and annoyance, but not quite enough to take off her attention from her conversation; so she goes on and takes no notice of Johnny's inquiry.

Johnny, accordingly, soon repeats it, "Mother! mother! what makes the rainbow ?" At length her attention is forced to the subject, and she either tells Johnny that she can't explain it to him--that he is not old enough to understand it; or, perhaps, scolds him for interrupting her with so many teasing questions.
In another such case, the mother, on hearing the question, pauses long enough to look kindly and with a smile of encouragement upon her face towards Johnny, and to say simply, "The sun," and then goes on with her conversation.