I thought: Let’s think of another simple task.

I thought arithmetic could be the simple task. So I taught him to count past 5 and he counted up to 5,557 over a period of three days before collapsing in sobs because he had not reached the end & I said with the genius of desperation that the good thing about infinity is that you know you’ll never run out of numbers. I taught him to add 1 to a number which seemed a simple task & he covered 20 sheets of graph paper with calculations: 1+1=2 2+1=3 3+1=4 until he was carried sobbing to bed. I once read a book in which a boy who studied too much at an early age came down with brain fever and was reduced to imbecility; I have never come across a case of brain fever outside a book, but still I was concerned & would have liked to stop but he sobbed if I tried to stop. So I taught him to add 2 to a number and he covered 20 sheets with 2+2=4 3+2=5.

How old was he asks a reader. I think he was about 3.