Hello There!
This is called a "PARADOX"
It is a statement that appears to be self-contradictory or silly, but which may include a latent truth.
One could be taking up for the other and get involved
Answer:
The purpose of the bobbin is to hold the thread that is held below the needle. The thread from the bobbin goes up through the plate and connects with the top thread to create a sturdy stitch when the machine is in use.