This very well could be the error he alludes to, which would be attempting to describe these changes, and understand them such that one can benefit from knowledge of how they came to be, in terms of the changes themselves, hence why he refers to them as "strands in the tangled affairs of men", because science does not take place in a vacuum, but rather a civilization, an institution, a field, a time, a region, etc.
Also, no analysis of such things is likely to be "final and exhaustive", because science is foremost an ongoing process, which means it is unfolding in the very moment that one seeks to explain it. And of course, because this process is one of the "tangled affairs of men", one can consider the following excerpts from Against Method: "[History is full of] accidents and conjunctures and curious juxtapositions of events...[and demonstrates the] complexity of human change, and the unpredictable character of the ultimate consequences of any given act or decision of men." - Herbert Butterfield
"History generally, and the history of revolutions in particular, is always richer in content, more varied, more many-sided, more lively and subtle than even the best historian and the best methodologist can imagine" - Lenin.
the way men think about things which are not themselves part of science, the historian of ideas has a similar problem.__