A scientist faces a challenge similar to that of a novelist staring at a blank page in his typewriter. You have to come up with a good story, that is, an important question or problem, and then methodically develop it. This involves lots of trial and error; for the writer this means experimenting with different characters, voices, scenes, styles, twists in the plot, and so on; for the scientist it means testing many possible hypotheses and ideas, and performing innumerable experiments. I would say that the formula for success in both cases requires a delicate mixture of somewhat contradictory ingredients: you need to be creative to come up with new possibilities and hypotheses, but extremely disciplined to carry out tedious work that may involve lots of repetition; you need to be skeptical of previous results (particularly your own), but adventurous in order to try new possibilities that may seem wild at first; you need to be bold to challenge an established view, but humble to listen objectively to criticisms of your own work. In graduate school, these tugs of war are barely noticeable at first, but then slowly become more intense.

If you're thinking about entering grad school, you must have had more than 15 years of experience in dealing with school life -- exams, homework, quizzes, projects, essays, etc. may all come as second-nature to you. However, graduate school is unlike any other educational experience. First of all, although you are required to do well in the courses, in the end they play a minor role; the most important factor is your own motivation to do the work. Highly successful graduate students work very hard, but nobody pushes them! They have an enormous curiosity and are genuinely interested in and passionate about what they do. Second, most of the work that students end up doing starts as a question and a general direction in which to search for the answer, but the road to get there is typically not well-defined. On the contrary, success often comes when a new question or the correct question is formulated. Ideas need to be continuously revised; new experiments or analyses that you hadn't realized were necessary keep cropping up; and things often don't come out as you expect. Even worse, sometimes many of the experiments you attempt simply don't work. Admittedly, this uncertainty is at times overwhelming. So, why put up with the frustration? Well, when things work, when you confirm a hypothesis that everybody thought was crazy, or you obtain an unexpected, exciting result, the feeling of accomplishment is exhilarating. Nothing beats it. Such craving for discovery is what brings many of us into the lab every day. That, and the hope that the results will eventually change things for the better.

The Howard Hughes Medical Institute has an interesting collection of opinions by leading investigators on what it means to become a scientist. Check it out here.