本来: A Room’s Original Use and a Tool’s Intended Purpose
Compare a room once used as an archive with a proposal to use tools for their intended purposes. Distinguish a past use from the standard for a proposed action.
本来 (ほんらい): The room’s original use
「この部屋は本来、資料庫として使われていた。」 — “This room was originally used as an archive.” The room was originally used as an archive. 本来 concerns its original use, presented as a past use.
資料庫 refers to the room’s original archive function here. The example describes a past use without specifying what the room is used for now.
本来の目的: A standard for using tools
「道具は本来の目的に合った使い方をしよう。」 — “Let us use tools in ways suited to their intended purposes.” The proposal is to use tools in ways suited to their intended purposes. 本来の目的 supplies a standard for their manner of use.
A proposal does not report that the tools were used accordingly. Nor does it establish that they were previously misused.
Past use and intended purpose
The room example concerns a former use; the tool example concerns an intended purpose. 本来 is not fixed as meaning a state opposite to the present.
Do not add a scene in which those tools were used in that archive. The separate examples describe an original use and a proposal about intended use.
What does 本来 refer to in the room and tool examples?
Show the answer and why
The room’s original use and the tools’ intended purposes. A current room use, previous tool misuse, and execution of the proposal are not added.