There's a famous story about an exercise from Lang's Algebra that says something along the lines of *"pick up a homological algebra book and prove all of the theorems yourself"*. I cannot find it in the third revised edition, and I'm wondering if it's still in the third revised edition, if it's only in the older editions, or if it's an urban legend.



"Pick up a homological algebra book and prove all of the theorems yourself" (exercise from Lang's Algebra)
It's real, but only in the first and second editions. (I don't have any electronic proof, but I've seen it in my copy of the second edition and someone else's copy of the first edition.) It's the only exercise in the chapter.


The full quote in the second edition is:



> 
> *Take any book on homological algebra,
> and prove all the theorems without
> looking at the proofs given in that
> book.*
> 
> 
> Homological algebra was invented by
> Eilenberg-MacLane. General category
> theory (i. e. the theory of
> arrow-theoretic results) is generally
> known as abstract nonsense (the
> terminology is due to Steenrod).
> 
> 
> 


If I'm not mistaken, the quote is the same in the first edition. First edition: page 105; Second edition: page 175; so you can look in your library to see if I messed up the quote!


And I do have an electronic copy of the third edition, which I've searched to confirm it is not there. The historical remarks were expanded, written less dismissively and put at the intro to Part Four.


**Update**: I've scanned the evidence. [First](https://drive.google.com/file/d/0B_pEp00B111JbkI4d2E1ZXdFWEU/view?usp=sharing&resourcekey=0-g4OtVvq9uUEM54B5nO8qYA), [Second](https://drive.google.com/file/d/0B_pEp00B111JYWU1NmY4MjktZTNmMS00MDE4LTkxMjQtYzQ4NWIxZjc3ZGY3/view?usp=sharing&resourcekey=0-O2_eiGXtzkhnXxk86ZS_Hg).


