Conceptualization of 'по'

Question

I am having a hard time sometimes conceptualizing 'по' when I come across it in my reading.

Take for example a sentence from Bulgakov: 'Трудно сказать, что именно подвело Ивана Николаевича – изобразительная ли сила его таланта или полное незнакомство с вопросом, по которому он писал...'

When I read this sentence, I view the 'по' as 'along' or 'according to,' but doesn't seem to feel right in this context (writing along or according to a question).

If I were to construct a sentence like this myself (from English into Russian)-- 'whether it was the descriptive power of his talent or complete unfamiliarity with the question he was writing about...' I would maybe write it as 'незнакомство с вопросом, над котором он писал' или 'о том, что он писал', but not using 'по.'

To reiterate, what should I know about 'по' so I am in a better position to understand what I am reading or hearing and how can I personally better incorporate it in my speech and writing? I know this is a broad and more theoretical question, but comments and insights are very much appreciated.

Answer 1

По is a very versatile preposition with a lot of abstract meanings that one doesn't intuitively associate with its perceived "literal" meaning of moving over a surface. It may perhaps be easier to consider its individual usages separately, almost as if it were different prepositions.

I don't have sources for this but from what I can tell by looking at the bigger picture of Slavic languages, the original literal meaning of по was most likely "after", or something similar ultimately referring to the action of following. In the particular case of Russian, what I think happened was that its meaning of "following" a path, trail, etc. branched off into a more general meaning of moving over any surface, not necessarily one that suggests a direction; that meaning eventually superseded the original one, but many of the more abstract usages of по still have "following", rather than "surface", as their underlying metaphor.

Answer 2

The meaning of the preposition "по (вопросу)" in your example is close to that of 'on' in the expression 'on that subject' ('lack of knowledge about the subject he was writing on').