Perhaps I can make it plain by analogy.
Imagine a machine, not yet assembled,
Each part being quite necessary
To the functioning of the whole: if the job is fumbled
And a vital piece mislaid
The machine is quite valueless,
The workers will not be paid.
It is just the same when constructing a sentence
But here we must be very careful
And lay stress on the extreme importance
Of defining our terms: nothing is as simple
As it seems at first regard.
“Sentence” might well mean to you
The amorous rope or twelve years” hard.
No, by “sentence” we mean, quite simply, words
Put together like the parts of a machine.
Now remember we must have a verb: verbs
Are words of action like Murder, Love, or Sin.
But these might be nouns, depending
On how you use them –
Already the plot is thickening.
Except when the mood is imperative; that is to say
A command is given like Pray, Repent, or Forgive
(Dear me, these lessons get gloomier every day)
Except, as I was saying, when the mood is gloomy –
I mean imperative
We need nouns, or else of course
Pronouns; words like Maid,
Man, Wedding or Divorce.
A sentence must make sense. Sometimes I believe
Our lives are ungrammatical. I guess that some of
Have misplaced the direct object: the longer I live
The less certain I feel of anything I do.
But now I begin
To digress. Write down these simple sentences:
I am sentenced: I love: I murder: I sin.