My fascination with the preposition, which I think is the most interesting part of speech, began as a gradual realization that it is the most conceptual element in the average sentence. Disregarding specific grammatical ordering, most simple sentences look something like this:

{Subject noun}{verb}{preposition}{object noun or noun phrase}.

Adjectives and adverbs can be added as descriptors, but the most basic sentence contains at least the elements I've listed. Of those elements, all could potentially be considered 'conceptual language', meaning that it could be part of a construct, or conceptual model, and not necessarily referring to a 'concrete' object or process.

Not all simple sentences need a preposition. Some are simply a noun and verb: "I wrote." Without an object, however, that sentence doesn't say very much, unless it's a reply in the context of a discussion. The sentences needs a prepositional phrase to be of much value as a declarative sentence.

Sentences that contain 'direct objects' don't have prepositions, either: "I ate an apple." These sentences tend toward the less abstract. They convey specific information, but of the more concrete variety.

The subject noun could be conceptual, and not concrete, in nature, if it is a pronoun, or if it is an abstraction, or a 'process as object'. An "-ism" is an example of a conceptual noun. I won't spend much time on that topic here. Perhaps I will in a later entry.

The verb could be conceptual if it references a hypothetical action, or a conceptual action. Some conceptual sentences use a verb as a 'state of being': "I stand alone." In this case, the verb "stand" is not meant literally.

It could also be highly metaphorical: "The idea ran through my mind." Again, I might spend more time on these ideas later.

That leaves the preposition. Though other parts of speech may be conceptual in nature, I would argue that the preposition is always conceptual. The purpose of this part of speech is to provide a direction, a perspective, and in so doing provides a sense of motion. The subject may be the destination, but the preposition is the journey. Something is going 'to' something, or coming 'from' something. Something can be 'above' something, or 'by' something, or 'under' something, or 'around' something, or myriad other relative positions.

Since I've not published anything on this blog for months, I will leave it at that for now.