Provenance
Where it comes from.
'Source' comes through Old French sourse, the rising or fountainhead of a river, from Latin surgere, 'to rise, spring up.' A source was first the place where water breaks the ground; by the late 14th century it meant a first cause or origin, and by 1777 the person or work that supplies information.
The small word 'in' marks place and belonging, an Old English preposition among the most worn and useful in the language. Together they read as an action and its setting: something found, and where it was found.