It is quite easy to understand the relative facts of a feline life. If you have eaten a delicious meal of tuna fish, devoured a mouse or even captured a bird, there are traces left and so you begin to remove the traces. For what do you have a tongue? The humans also have a tongue, but being a primitive race, they have not yet discovered the main facets of the tongue.
My tongue is a versatile object, can be stretched and reaches every nook and cranny of my delightful body. You can lick your paw and use it as an accessory to the washing ritual. How can you otherwise reach behind the ear, and my mum always said make sure you have clean ears.
Always wash after eating is the idea. We do not want other felines smelling what you had for dinner. They might get jealous and this can lead to a paw argument. It is all a question of relativity What you have eaten and when you ate it, and the reaction on the feline mechanism.
For example, just take a blade, a few blades, a whole clump of grass. It does not taste very good, but a grass munch has its advantages, especially if you have indulged in eating hard vitamin pellets before eating the grass. You feel the influence of the grass, it is a chemical reaction with the vitamin pellets and the result is the manufacture of the most perfect hairball. This cannot be achieved by eating normal food, such as mouse or bird, or even tuna fish. No, the ultimate solution is pellet garnished with grass. It is very organic and produces a cataclystic reaction. It is all a matter of using the right manoever when the hairball is born. It is better to hide the hairball from prying human eyes afterwards, otherwise it does not have a chance to dehydrate and form the perfect shape. Mrs. Human tends to get hysterical when a hairball production is happening. And we felines know that hairball production is something special, almost sacred, to the feline race.
Kittens I hope you are paying attention to the technical details.