ENGELS TO JOSEPH DIETZGEN$*’ 
[Excerpt] 
[London, 31 December 1884] 

So for the time being I can hold out no prospect of being able to 
contribute to your paper. But should I happen to take a holiday, and 
should something then turn up, or if events were to take place which 
would render my assistance of real use, it goes without saying that 
I should at once make myself available.