Vigenere cipher with a shared resource
Since your key is non repeating, you're essentially talking about one-time-pad, not a vigenere cipher.

There are two problems with what you propose:


The key is natural language. This means that the key acts like a second use of the pad. This is enough to recover the plaintext with few mistakes.

The one-time-pad doesn't just require a long enough key, the key must also be perfectly random.
The shared text is public knowledge, and thus presumably known to the attacker. So the attacker could simply test every text in their library against your ciphertext. This is quite feasible using computers, even for huge libraries.