A baby's need to explore his world must be satisfied if deep frustration and later depression are to be avoided. The more eager, restless and inquisitive the child, the more potential there is for such frustration and the greater the need for careful organization on the adult's behalf. He will be fascinated by variations in sound, light and pattern. A baby's needs can be satisfied without great expense. The average household is an Aladdin's cave of interest and delight to the innocent eye.
Toys involve expense, and some are very expensive indeed.
Buying toys therefore needs careful thought. A baby's interest in the toy is going to be very different from an adult's appreciation of it. A toy is to a small child, not itself, but a 'possibility' - an object to be examined to its last element, to be figuratively and often literally 'taken to pieces' until every aspect has been explored for its interest and fun. There is no point in giving a child a toy which does not allow this or where the adult disapproves. In that case for adult and child there is only disappointment and anger.