This question is asked myself each. It's so interesting what happens in the mind of malnekogo child who can not even speak. So let's deal:
Some children are born bilingual. For example: If the mother during pregnancy speak two different languages, that her baby is able to distinguish between them. Children from 4 to 6 months can read lips: they know what language a person says, even if watching a video with the sound turned off.
6-month-old children distinguish between good and evil characters.
In 10 months, the children are able to notice the difference between objects. For something new and wonderful children react as adults: look at it longer.
15 month old children have a sense of justice. For example, if you share a cookie between two adults and one will get more than a cookie, it is likely that the child is leveled Number of cookies.
This is just a small part of what is happening in the child's head. Perhaps in the future date science can discover all the secrets of man. But for now, you can just watch and enjoy as our children grow.