2
Saturday. (Beginning perhaps amended.) I know it is madness to keep this journal but it gives me a strange thrill to do so; and only a loving wife could decipher my microscopic script. Let me state with a sob that today my L. was sun-bathing on the so-called “piazza,” but her mother and some other woman were around all the time. Of course, I might have sat there in the rocker and pretended to read. Playing safe, I kept away, for I was afraid that the horrible, insane, ridiculous and pitiful tremor that palsied me might prevent me from making my entre with any semblance of casualness.
(Lolita, Vladimir Nabokov)
The event time of ‘might prevent’ exists since the time of ‘kept away,’ and so ‘might have prevented’ would not be possible, I think. But, when we shift the reference time of ‘might prevent’ from the past to speech time (the present), we could say ‘may prevent’ instead of ‘might prevent,’ without breaking semantic order. (Of course, though ‘might prevent’ is able to denote present tense, I’m asking for the use of ‘may.) Is it possible or is there some problem?
1Actually, it seems to me that the "might prevent" phrase should be "might have prevented" because the sentence describes a completed event in the past using a hypothetical condition (what some people call a 3rd conditional?). Perhaps it's related to the way some people use "must" as a past tense in, eg, "I knew then that I must keep moving or I'd freeze to death, so I just kept pacing back and forth to keep my temperature above 90F". I'd use had to instead of must. I think it's typical of British English & 19th- & early-20th-century American English. I don't think it's wrong. – None – 2013-05-06T09:11:15.190
1After reading Brian's answer & rereading your question, it's clear to me that you've misunderstood the context of the passage. HH is writing about something that's over & done with. The reference time can't be shifted to the present. Only his writing can be considered "present" (ie, you're reading it as he's writing it, but it happened before he wrote it). – None – 2013-05-06T10:20:57.120