Recently I had a "special" class that I taught to 7th graders for a few weeks, in the context of the test-prep period. It was supposed to be a grammer-focused writing class, and because most of the students were fairly low level (although it was a mixed group and there were some high level students too), I decided to basically focus on a single grammer object: the "to" infinitive forms of English, since they are used in a lot of ways and in a lot of different expressions.
As part of this, I found myself wondering about the etymology of the "to" particle, which is most definitely not the same as the homonymous preposition by modern linguistic descriptions, but which seems to bear some weird traces of what one might call "prepositionality." Was the origin of the "to" particle related to the preposition "to" or was it a coincidence (a linguistic merger)?
It was actually a bit difficult to research, but finally I found some text that confirmed that the infinitive "to" is, in fact, derived from the preposition "to." That is interesting to me, and because it was so hard to find out, I decided to blog about it, so if I want to go back and look it up again in the future, it's in my aide-memoire blog thingy.
Here is the authoritative quote I found:
The English so-called 'infinitive marker' (or 'infinitive prefix', 'infinitive particle') to derives from the dative-governing preposition used with an inflected infinitive to express purpose. In this sense, it can be considered to represent the universally well-known grammaticalization path 'purpose > infinitive' (Haspelmath 1989; Heine & Kuteva: 247-248), whereby the preposition is desemanticized and acquires distributional properties not found with, or not typical of, noun-governing prepositions. - from John Ole Askedal, in Grammatical Change and Linguistic Theory: The Rosendal Papers, page 63.
[daily log: walking, 1km]