Why didn't I think of this?

Jonah: "Mom, you forgot something that I need for when Eli is bigger and we have a dog and we play in the forest." Me: "I did? What is it?" Jonah: "A gun." Me: "A gun?" (That is the last thing Jonah will ever need. At 4yo he still falls off his chair at the dinner table.) Jonah: "Yes, a gun. For when we see bears and deer. So they don't hurt us." Now, why didn't I think of that? How could I not see deer as a threat?