Old English findan "come upon, meet with; discover; obtain by search or study" (class III strong verb; past tense fand, past participle funden), from Proto-Germanic *findan "to come upon, discover" (source also of Old Saxon findan, Old Frisian finda, Old Norse finna, Middle Dutch vinden, Old High German findan, German finden, Gothic finþan), originally "to come upon."
The Germanic word is from PIE root *pent- "to tread, go" (source also of Old High German fendeo "pedestrian;" Sanskrit panthah "path, way;" Avestan panta "way;" Greek pontos "open sea," patein "to tread, walk;" Latin pons (genitive pontis) "bridge;" Old Church Slavonic pǫti "path," pęta "heel;" Russian put' "path, way;" Armenian hun "ford," Old Prussian pintis "road"). The prehistoric sense development in Germanic would be from "to go" to "to find (out)," but Boutkan has serious doubts about this.
Germanic *-th- in English tends to become -d- after -n-. The change in the Germanic initial consonant is from Grimm's Law. To find out "to discover by scrutiny" is from 1550s (Middle English had a verb, outfinden, "to find out," c. 1300).
pathfinder n.
"one who discovers a way, an explorer or pioneer," 1839 (Cooper), from path + finder.
"Pathfinder!"
"So they call me, young woman, and many a great lord has got a title that he did not half so well merit; though, if truth be said, I rather pride myself in finding my way where there is no path, than in finding it where there is. But the regular troops are by no means particular, and half the time they don't know the difference between a trail and a path, though one is a matter for the eye, while the other is little more than scent."