Dijkstra was famous for his wit, eloquence, rudeness, abruptness and often cruelty to fellow professionals, and way with words, such as in his remark, "The question of whether Machines Can Think (…) is about as relevant as the question of whether Submarines Can Swim.". His advice to a promising researcher, who asked how to select a topic for research, was the wise words: "Do only what only you can do". Dijkstra was also known for his vocal criticism and absence of social skills when interacting with colleagues. As an outspoken and critical visionary, he strongly opposed the teaching of BASIC.