A baby's existence for the first three months is a one-way street. One person is doing all the work and the other is crying, sleeping and pooping. So the first moment when you're actually able to do something and they acknowledge your presence, that's a big deal. A very big deal.
“The parental, and filial affections seem to be as ardent, their sensibility and attachment, as active and faithful, as those observed to be in human nature.”