I once heard a lecture on the poetry of Bob Dylan, in which the lecturer described the tension in the lyric "Lay, lady, lay /Lay across my big brass bed" as deriving from the fact that it should be "Lie, lady, lie," but the singer fears that by uttering the word "lie" he might open up the possibility of her lying to him, turning their love into a falsehood.
Sally Alexander -- longtime English teacher at the Holton-Arms School in Bethesda, Md. -- offers this perspective on those oft-misused verbs to lie and to lay.
Principle parts: lie (pres. tense) lay (last tense) lain (participle). This verb is intransitive - i.e., does not take an object. E.g., I lie on my bed, yesterday I lay on my bed, I have lain on my bed all day. (On my bed is an adverbial prepositional phrase, not an object.)
Principle parts: lay (present tense), laid (past tense), laid (participle). This verb is transitive - i.e., must take an object. E.g., I lay the book on the table, yesterday I laid the book on the table, every day this week I have laid the book on the table.
I once had a male teacher in the English department at Holton who, when I pointed out that these two verbs should be taught in the ninth grade, told me, "Teach it somewhere else. I'm not telling fourteen year-old girls that you can lie by yourself, but you have to lay something."