My brain learns from everything that it experiences. That's what neurologists call a "plastic" brain.

If I lose my eyesight, my brain shifts those neurons to my other senses; I may end up with more acute hearing or the ability to smell a hot chocolate-chip cookie from half a mile away. It's a remarkable way of diverting neurological resources to where they are needed most.

But God designed us to love, not to fight, so war traumatizes our brains. We end up with images scared into it that we can't forget, can't escape.