The bedrock of grammar, at least the grammar of English and other languages like it, is the connection of a subject and a verb. We speak or write a sentence because we have something to say about something. What we’re saying something about is called the subject, and what we’re saying about that subject is called the predicate. The center of a predicate is the verb, and so when we combine a subject with a predicate, we’re really saying something, sentence by sentence, until we’ve had our say.
The trick in saying something well—in being clear and easily understood—rests on choosing the right words and putting them in the right place in a sentence. And one of the reasons so much is made of the subject/predicate distinction in traditional grammar is that it gives us a reliable way to find and maintain the central axis of a statement, the point around which the other words can rightly take their place. Unlike some other languages, English word order is fairly rigorous: first the subject, then the verb, then the object if there is one. So if I want to say something about a friend of mine and I tell you that she runs a couple of miles every other day, the pronoun she is the subject, which is then followed by the verb runs, which in turn is followed by the direct object a couple of miles.
This particular predicate, though, also includes an adverbial phrase, every other day, and here’s where finding the subject can get problematic as we read or compose more sophisticated and interesting sentences. Adverbs point to the time or place or manner in which something is being done, and so they most often modify the verb, which means they logically belong in the predicate, as is the case in the layout of our example. Words that work together stay close together, but on that same principle adverbs can be placed in a number of different positions across a sentence, settling on a place where they can emphasize one idea instead of another. That’s all great, but it can make it difficult sometimes to identify the subject of a sentence when we’re expecting the subject to appear first.
If, for example, I wanted to emphasize the fact that every other day, if you can believe it, my friend runs a couple of miles, then I could move that adverbial phrase to the initial position of the sentence: Every other day she runs a couple of miles. That sounds a little odd in an isolated statement like this, but if I had been going on about how disciplined this friend of mine was, I might accentuate the rigor of her determination by beginning the sentence with this notion of time. But what then has happened to the subject, which the subject + verb + object word order implies should come first? Now we seem to be talking about a day.
If we think about this grammatically, looking first at the structure of the revision, all that has really happened is that a predicate element, here the adverbial phrase every other day, has left its likely home next to the verb, runs, and has assumed new quarters at the head of the sentence for purposes of emphasis. It has taken a place outside the predicate where logically it doesn’t belong, but where stylistically it has every right to be. And if we can remember that this happens all the time in English, we won’t then be thrown into confusion when we’re analyzing a sentence to find its subject and verb. Nothing is being said about the day, and so that noun, even though it appears first in the sentence, cannot be the subject. Day might be a neighbor to she, but only one of them holds ownership as subject of the sentence.
The standard word order of subject + verb + object is a good working rule, but it, like all rules, must be handled deftly if we intend to write with any natural complexity. Analysis is an essential but ultimately artificial procedure, and to wield it well, we have to be ready for any order in which writers (and more often speakers) may assemble their words. A little grammatical alacrity on the part of both is a good thing.