When milk is spilled onto the floor, to put it in a very clique manner, it is only natural for us to cry over the spilled milk.
All advanced species on earth, including human beings, have strong propensity towards the display of emotion, and we often use the outpouring of emotion, whether in happiness or in sadness, as a means to maintain equilibrium over our general well-being. In other words, it is only natural for us to remain upset over a loss in the past, even if there is absolutely nothing we can do to restore the situation completely to the state before the offending event that caused the loss. This is so that we can purge the unhappiness that is generated as a result of the offending event from our body so as to maintain the steady state in our body.
As in the case of the spilled milk, it is obvious that when the milk has been spilled, it is already wasted and therefore cannot be used in the normal hygienic sense. Nevertheless, the process of crying cleanses our body of the negative emotions generated so that our body can begin to heal in an effort to restore equilibrium once again. Perhaps then, we can once again see the cat playing his fiddle on the kitchen counter while the cow jumps over the moon formed from the spilled milk. The little dog then shall laugh heartily to see such fun, and perhaps even the dish will ran away with the spoon.
N.B. the imagery as described in the last sentence is taken from a nursery rhyme named “Hey Diddle Diddle”. The original version goes something like this:
"Hey diddle diddle,
The cat and the fiddle,
The cow jumped over the moon,
The little dog laughed to see such fun,
And the dish ran away with the spoon"
The purpose of introducing such a ludricious imagery in the midst of trying to come to terms with the sense of loss over the spilled milk is to encourage ourselves to try using humour as tool to resolve internal conflicts. It works surprisingly well when we are able to see the world from the funnier perspective.