When Gandhi writes "Only I had been stupid", what does he really mean?

I do not remember having ever told a lie, during this short period, either to my teachers or to my school-mates. I used to be very shy and avoided all company. My books and my lessons were my sole companions. To be at school at the stroke of the hour and to run back home as soon as the school closed,—that was my daily habit. I literally ran back, because I could not bear to talk to anybody. I was even afraid lest anyone should poke fun at me.

There is an incident which occurred at the examination during my first year at the High School, which is worth recording. Mr. Giles, the Educational Inspector, had come on a visit of inspection. He had set us five words to write as a spelling exercise. One of the words was ‘kettle’. I had mis-spelt it. The teacher tried to prompt me with the point of his boot, but I would not be prompted. It was beyond me to see that he wanted me to copy the spelling from my neighbour’s slate, for I had thought that the teacher was there to supervise us against copying. The result was that all the boys, except myself, were found to have spelt each word correctly. Only I had been stupid. The teacher tried later to bring this stupidity home to me, but without effect. I never could learn the art of ‘copying.’

Yet the incident did not in the least diminish my respect for my teacher. I was by nature blind to the faults of elders. Later I came to know of many other failings of this teacher, but my regard for him remained the same. For I had learnt to carry out the orders of elders, not to scan their actions.