Bizarre theories of bird migration from the 17th century

Where do birds go in the winter? Scientists admit they have't completely cracked this mystery, even now - but you won't believe some of the strange and delightful conclusions drawn by academics of the 1680s.

For what was essentially a simpler time, these theories are surprisingly, um, complex. Kate Romano explains.

Click through to the episode of Essential Classics from 13 September to hear more.