Equivalence of Traversal Verb + て and で of Means/Instrumentality

Question

Consider:

• XにYで行く
  • 学校に自転車で行く
    • "Go to school by bicycle" ("means/instrumentality" interpretation)
    • "Is* bicycle and go to school" (Questionable?) (Verb conjunctive interpretation)
• XにTraversal Verb-て行く
  • 学校に歩いて行く
    • "Go to school by walking" ("means/instrumentality" interpretation)
    • "Walk and go to school" (Verb conjunctive interpretation)

The leads me to ask:

• Does て-form implicitly contain the で of means?
• Or is the で of means a て-form of something *(the copula だ perhaps?)

There seems to be something common between て-form and で of means.

Answer 1

Simply, yes, で is just the 〜て form of だ. You could get into a whole discussion on this, but we can see the parallels between them.

Connecting

• イ-adjective: 大きくて強い　→　Big and strong
• ナ-adjective: きれいで頭がいい　→　Pretty and smart

Means/instrumentality

• Verbs: 行ってくる　→　Go and come back ("Come back by means of (first) going")
• Nouns: お箸【はし】で食べる　→　Eat by using chopsticks

As I said, this is an overly-simplistic answer, but I don't have time right now to jump into all of it.