This was one that always confused me. I knew of course the lie – lay distinction, but, despite that distinction, the expression I had always heard was to lay low (which of course should be to lie low). A simple Google search reveals that it should in fact be lie low, but that didn’t explain where the lie low v. lay low confusion originated. In researching further, however, I found this entry on Wiktionary, that explains that there is in fact an expression to lay low, which means something very different and in fact maintains the correct usage of lay. Lay low means to knock someone out (He was laid low by the stone), while lie low means, as we know the more common expression, to hide out.
In general, lie vs. lay is an example of transitive vs. intransitive verbs. Transitive verbs are verbs that can take a direct object; intransitive verbs are verbs that cannot take a direct object. There are plenty of common and of-confused pairs of such verbs: rise, raise (the sun rises but I raise my hands; I can’t rise my hands); and my personal favorite: itch, scratch (your arm can itch but you can’t itch your arm; rather, you can scratch your arm).
Lie v. lay, however, is a particularly confusing pair because their principal parts overlap: lie, lay, lain (and, yes, lain is a word, however infrequently used it might be) vs. lay, laid, laid; that lay as past tense of lie but present tense of, well, lay is what gets everyone. The trick is the direct object. In the present, lie cannot have a direct object, lay must have a direct object. In the past, lay cannot have a direct object, laid must have a direct object. (Grammar Girl has some nice graphics that help with this distinction / explanation.) Some examples:
- Today, I am lying on the couch (correct)
- Today, I am laying on the couch (incorrect)
- Today, I am laying the book down (correct)
- Yesterday, I lay on the couch (correct)
- Yesterday, I was laying on the couch (incorrect)
- Yesteday, I was lying on the couch (correct)
- Yesterday, I was laying the book down (correct)
- Yesterday, I laid the book down (correct)
A fun footnote to all of this is the verb to suck. A few years back, Oxford reclassified suck, making it merely slang rather than its previous designation of vulgar. The reclassification hinged on the shift of the verb suck from a transitive verb to an intransitive verb. As a vulgar, transitive verb, when something sucked, it was sucking something. As a merely slang, intransitive verb, now something just sucks. (That is unfortunately one that I cannot use in class; or that I at least have to use judiciously….) (And I could have sworn William Safire wrote about this in the New York Times, but I can’t seem to find the article.)