1. 1〔話の主題目〕
    • 本筋に入る
    • 「take up [move on to] 「the main topic [the central theme] ((of one's talk))
    • 本筋を外れる
    • digress from one's [the] main subject/get off the subject ((of one's talk))
    • 話を本筋に戻すと…
    • Getting back to our main subject....
  1. 2〔正当な筋道〕
    • まず彼に相談するのが本筋でしょう
    • The proper thing would be to consult him first.