This is the title of an inspiring talk by Richard Hamming (1915-1998), a mathematician, who "who discovered mathematical formulas that allow computers to correct their own errors, making possible such innovations as modems, compact disks and satellite communications" (New York Times Obituary).
It can be found here. It appears to me that his advice is sound not just for research in science, but also for research in the Liberal Arts, or indeed in any pursuit.
"'Knowledge and productivity are like compound interest.' Given two people of approximately the same ability and one person who works ten percent more than the other, the latter will more than twice outproduce the former. The more you know, the more you learn; the more you learn, the more you can do; the more you can do, the more the opportunity - it is very much like compound interest. I don't want to give you a rate, but it is a very high rate. Given two people with exactly the same ability, the one person who manages day in and day out to get in one more hour of thinking will be tremendously more productive over a lifetime."
"If you do not work on an important problem, it's unlikely you'll do important work. It's perfectly obvious. Great scientists have thought through, in a careful way, a number of important problems in their field, and they keep an eye on wondering how to attack them. Let me warn you, `important problem' must be phrased carefully."
"Most great scientists know many important problems. They have something between 10 and 20 important problems for which they are looking for an attack. And when they see a new idea come up, one hears them say 'Well that bears on this problem.' They drop all the other things and get after it."
Perhaps the "important" is not so important in disciplines other than the natural sciences, if only because one might say that the criteria for the importance of problems are much more vague there, which may be taken as another way of saying that all the problems are important (and that would, of course, be another way of saying that none of them are). So, let's keep it at "much more vague."
What is important, however, is that one has problems that need solving, for without problems there is no real thought, or so I would argue.