There comes a moment (though not always) in research when all the pieces begin to fall into place, as in a jigsaw puzzle. But unlike the jigsaw puzzle, where all the pieces are near at hand and only one figure can be assembled (and thus the correctness of each move be determined imme­ diately), in research only some of the pieces are available, and theoretically more than one figure can be made from them. In fact, there is always the risk of using, more or less consciously, the pieces of the jigsaw puzzle as blocks in a construction game. For this reason, the fact that everything falls into place is an ambiguous sign: either one is completely right or completely wrong.

— Carlo Ginzburg & Adriano Prosperi,
Giochi di pazienza: Un Seminario sui “Beneficio di Cristo”
Turin: Einuadi (1975) p 84