  Part of a collective mood arises at the point of contact between esoteric and  exoteric circles. On the one hand, members of exoteric circles usually trust  professionals and they admire them. On the other hand esoteric circles act under  pressure of expectations of the masses. When a certain domain lacks support from  outside, it does not have significant achievements. Fleck here uses an analogy  of sand carried by the wind. A rock sometimes hits its target and sometimes it  does not, whereas sand carried by the wind unavoidably accumulates in hollows  (1935a, III). So when some social pressure makes enough researchers work long enough on a certain issue and obtain sufficient material support, they finally arrive at more or less satisfying results. A condition of success is not the alleged truth of employed theories but the systematicity of research.