difference between for a long time and for long

[ansonguy]

I am going to make up two similar sentences below.

(1) He didn't read novels for a long time.

(2) He didn't read novels for long.

Some of my non-native English speaking friends think the two phrases make the sentences have different meanings. I don't see why. Can someone please explain the difference? Thank you very much.

 

[emsr2d2]

They do have different meanings. The first one suggests that, at some point in the past, he spent "a long time" without reading a novel. Perhaps he didn't read a novel for a period of ten years (it depends what the writer considers to be a long time).
The second suggests that he used to read novels and, when he read them, he only read for perhaps five or ten minutes at a time. He didn't read a novel for, say, two hours solid.