Because ...
Tell me again, what will happen when T cells' education fails? What will happen when they fail to bind only to foreign antigens or self-MHC molecules, and they bind with self-antigens instead? Here's the clue: A ... s.
Apoptosis.
Die. They'll die. Poor T cells.
T cells' failure in education brings annihilation upon themselves. Our failure in our learning process could cause the same thing, though not in the literal sense.
In this life, selection is all around us. When we want to get into a school or a university, there are tests specifically designed to sort out the applicants. When we want to get a job, there are interviews and stuff. They're all selections that are designed to select only the applicants who meet the requirements needed by the institution.
If we fail to educate ourselves, we might not be competent enough to pass a certain selection. And if it's a selection of paramount importance, our failure might be a contributing factor to our figurative destruction. Say we want to get a job or create a job, but we can't because we lack both the knowledge and the experience - which we could get from the learning process - pertaining to the job, then we do nothing, our life becomes miserable, and a miserable life silently destroys us. Or you know, something like that hehe.
So, you see it now?
We're all alike, T cells and us!
Don't you find it wondrous? The fact that Allah makes even the minuscule parts of our body similar to ourselves amazes me. The fact that even the cells and the system in our body seem as if they possess something like human nature - which is the need to learn - is wonderful. The fact that a system inside our body is similar to a bigger system in our general life is just one of so many Allah's gifts for us to be grateful for.
So when we find ourselves too lazy to study, remember that our need to learn is a basic human nature that we must not (and can't) run from. Meanwhile, the selection that follows it is a part of a more complex system which we can't avoid. The learning process and the selection are inevitable, even our little T cells experience those too.
