Roald Hoffman in American Scientist:
The title phrase, said with just the right intonation, could be dismissive: a polite, thinly veiled way of saying “I am not really interested.” But my concern here is with the sincere variant of the expression—particularly in science, when it is said to oneself, sotto voce. For this statement is how curiosity is stirred. And, as I will argue in a continuation of a small campaign to value the “unmathematicizable” in science (I’ve also written about the importance of metaphor and storytelling), psychological interest is a progenitor of scientific creation itself.
As a descriptor of an experiment or theory, interesting resides more or less comfortably between beautiful and strange. Aesthetic judgment, such as attribution of beauty, is generally avoided by scientists as they write—paradoxically so, I’d say, for they would like nonscientists to value not just the technological utility of their labors, but also the elegance. Is it reticence that leads one to avoid writing “this molecule is beautiful” in a scientific paper? No, I think it is a fear of the spiritual, as if calling a molecule beautiful in a paper would put one in the company of art critics. Or, God forbid, priests. And strange, when used to describe a scientific observation, can carry a hint that something might be amiss: a spectrum not quite correctly interpreted, a mistake of sign in a derivation. But interesting, when said without a veiled smirk, is very much a positive valuation. That is, as positive about other people’s work as scientists often allow themselves to be in public.
More here.