before 900;Middle English (preposition and adv.), metathetic variant of thourgh,Old Englishthurh, cognate with Germandurch; akin to Old Englishtherh,Gothicthairh through, Old High Germanderh perforated, Old Englishthyrel full of holes (adj.), hole (noun). See thirl
By,through,with indicate agency or means of getting something done or accomplished. By is regularly used to denote the agent (person or force) in passive constructions: It is done by many; destroyed by fire. It also indicates means: Send it by airmail.With denotes the instrument (usually consciously) employed by an agent: He cut it with the scissors.Through designates particularly immediate agency or instrumentality or reason or motive: through outside aid; to yield through fear; wounded through carelessness.
c.1300, metathesis of O.E. þurh, from W.Gmc. *thurkh (cf. O.S. thuru, O.Fris. thruch, M.Du. dore, Du. door, O.H.G. thuruh, Ger. durch, Goth. þairh "through"), from PIE base *tr- "through" (cf. Skt. tirah, Avestan taro "through, beyond," L. trans "beyond," O.Ir. tre, Welsh tra "through"). Not clearly differentiated from thorough until early Mod.Eng. Spelling thro was common 15c.-18c. Reformed spelling thru (1917) is mainly Amer.Eng.
In every part or aspect, throughout. For example, I was wet through and through, or He was a success through and through. This idiom originally was used to indicate literally penetration, as by a sword. The figurative usage was first recorded in 1410.