And everywhere he would see these same infants being forced to drink milk. How horrid, he would say. How disgusting. How terribly low class.
Many advocates of breast feeding argue that, in the natural way of things, and based on observations of other large primates, humans might be expected to suckle their young until they reach the age of seven.
That this is rarely the case, they say, is a measure of how we, uniquely among animals, allow belief and custom to modify our actions. And it seems to be true that the more highly civilised human societies are reckoned to be, the more they prefer to distance themselves from the act of suckling.
In northern Europe in the 18th century, the powdered wig brigade considered offering a baby the breast to be downright common. And in Austria, for a time, any kind of milk diet, be it from breast, bottle or bucket, was thought to be quite unsuitable. Instead, babies born to respectable families were largely raised on sugar water - a practice which Mozart's parents considered most proper, as did Wolfgang Amadeus himself on becoming a father.
Can a baby survive on sugar and water? Human milk is surprisingly low in fat and protein, and correspondingly high in carbohydrates such as lactose, a type of sugar. It is the lactose that feeds the growing brain, which may be why there is twice as much of it in human as in cows' milk.
But without fat intake, a child will be sickly overall, which is possibly why four of Mozart's six children died within three years of their birth, and their father's own life was cut tragically short.
As to whether listening to music affects children's development, nobody can be sure either way. But one thing is certain. When it comes to feeding them, on no account should their mothers listen to Mozart.