The school at Seville was the first of its kind in Spain. All the ordinary school subjects were taught, and the boys were made to work very hard. Isidore, like many boys, disliked hard work, and one day he played truant from school. In fact, he intended to run away altogether; but, as the sun was very hot and he soon became very tired, he sat down to rest beside a little spring that gushed over a rock. As he was resting in the shade he noticed that the stone on which the drops of water fell had been worn away, and he thought: If drops of water can actually make a hole in a hard stone by never ceasing to fall, surely if I persevere with my lessons I shall gradually get to like them and not find them so dull and difficult. So that evening he went back to school and before long became the best scholar there.
Hugh Ross Williamson in The Young People's Book of Saints from The Catholic Company