In a message dated 26/03/2008 13:47:35 GMT Standard Time,  
[log in to unmask] writes:

David,  this is a fascinating question! Heeding Nancy's warning, I'm toying 
with  paraphrasing some of Eliot's lines in my own poetry, but a bit of the 
original  is needed to clarify the allusion. I'm wondering how many words in 
succession  constitute a quotation. For example what if I write: "Let us go then 
two by  two, double I and both of you" is that liable to the charge of 
copyright  infringement? 

The fine points of this law, especially when  considered for possible 
international application, are  maddening.


Mentioned here as regards US law:
_ ( 
In English copyright law there seems to be  precedent that '  a parody which 
is in itself  original having its origin in the work parodied was held not to 
infringe the  copyright in the work': Joy Music Ltd v Sunday Pictorial  
Newspaper (1920) Ltd  - a 1960 case.