My (perhaps entirely unhelpful) first reaction to this is that Sanskrit, due to its history and stylistic conventions, has many more words for pretty much anything than most other languages do, literary/ancient or not.

Also, my guiding principle in the questions you ask would be to make sure I keep questions of language/grammar and of literature/style very clearly separate. The one truly linguistic aspect of a language that could express its 'psychological complexity' to me would be its lexicon (unless we were to consider morphemes such as inclusive 'we' vs exclusive 'we' that are found in some languages, but not e.g. Sanskrit; or perhaps verbal moods that distinguish between 'would', 'could' and 'should', all expressed by the same verbal category in Classical Sanskrit). The main distinguishing features of the Sanskrit lexicon (I am here thinking especially of the fact that it has such a beautiful wealth of synonyms) seem to be due to the pressure to be innovative that writers using a grammatically fixed language could only channel in a limited variety of ways.

That said, I would be greatly interested in literature that shows my curmudgeonly attitude to be wrong:-).

All the very best,

     Antonia