'On' vs 'by', Which preposition should I use in the sentence?

Question

I purchased it on/by open account from creditor.(Sense-through the means of)

Which preposition is suitable here? Why?plz explain..

Answer 1

Which preposition to use is not reducible to rule.

In this case, it is “on open account,” which is business English not understood by 95% of native speakers. If you want to be more widely understood, say “on credit.”

Answer 2

Longstanding legal terms of art, like "On/by open account from creditor," are used by careful lawyers who fear that the use of modern terms—for example, "on credit"—could be deliberately misconstrued in order to break a contract. The use of "on/by" is an early example of writing typical of a boilerplate document. Another minor thing, also typical of a boilerplate, that makes "On/by open account from creditor" archaic and idiomatic writing is that it colloquially drops the usual article (the/an) that would normally precede a noun like "creditor" (the object of the pronoun "from").

More important, the prepositional phrase string "on/by open account from creditor" can be thought of as identifying a "creditor" (in this specific case, a creditor who is also a seller) who sets up an account on behalf of another. Another way to think of it is that the one who is receiving the "credit" gets it by the issuance of credit by the seller. The emphasis is different in the prepositional phrase "on credit," which identifies a process (credit granted) that sounds less intimidating; less like a one-to-one personal transaction and more like a business transaction. The trend is shorter, easier-to-understand phrases, like the more modern-sounding "on credit" (extended by a seller).

When not writing legalese, one can substitute the preposition "through" for the preposition "by" if, for whatever reason, one needs to use a different preposition. (I looked up the word "through" online in order to doublecheck that I do indeed use this preposition properly.) The prepositions "through" and/or less often "via" convey the nuance of "by means of some type of agent" and/or the nuance of time passing. Two examples: "I bought it through the Internet." ("Through" could also be "via," "from," or "on.") "They sent it to me via overnight mail." ("Via" could also be "by" or "through.")

References that influenced my comment:

1. Plain English for Lawyers, 3rd Ed., Richard C. Wydick, Carolina Academic Press c1994.

2. My internalization of the chapter on prepositions in Harper's English Grammar; A Complete Guide to Modern English Grammar and Usage, John B Opdycke, rev. & ed. by Stewart Benedict, Harper and Rowe, Publishers, c1966.