We have already seen that the major functional unit of speech, the sentence, has, like the word, a psychological as well as a merely logical or abstracted existence.  Its definition is not difficult.  It is the linguistic expression of a proposition.  It combines a subject of discourse with a statement in regard to this subject.  Subject and “predicate” may be combined in a single word, as in Latin dico; each may be expressed independently, as in the English equivalent, I say; each or either may be so qualified as to lead to complex propositions of many sorts.  No matter how many of these qualifying elements (words or functional parts of words) are introduced, the sentence does not lose its feeling of unity so long as each and every one of them falls in place as contributory to the definition of either the subject of discourse or the core of the predicate[7].  Such a sentence as The mayor of New York is going to deliver a speech of welcome in French is readily felt as a unified statement, incapable of reduction by the transfer of certain of its elements, in their given form, to the preceding or following sentences.  The contributory ideas of of New York, of welcome, and in French may be eliminated without hurting the idiomatic flow of the sentence. The mayor is going to deliver a speech is a perfectly intelligible proposition.  But further than this we cannot go in the process of reduction.  We cannot say, for instance, Mayor is going to deliver.[8] The reduced sentence resolves itself into the subject of discourse—­the mayor—­and the predicate—­is going to deliver a speech.  It is customary to say that the true subject of such a sentence is mayor, the true predicate is going or even is, the other elements being strictly subordinate.  Such an analysis, however, is purely schematic and is without psychological value.  It is much better frankly to recognize the fact that either or both of the two terms of the sentence-proposition may be incapable of expression in the form of single words.  There are languages that can convey all that is conveyed by The-mayor is-going-to-deliver-a-speech in two words, a subject word and a predicate word, but English is not so highly synthetic.  The point that we are really making here is that underlying the finished sentence is a living sentence type, of fixed formal characteristics.  These fixed types or actual sentence-groundworks may be freely overlaid by such additional matter as the speaker or writer cares to put on, but they are themselves as rigidly “given” by tradition as are the radical and grammatical elements abstracted from the finished word.  New words may be consciously created from these fundamental elements on the analogy of old ones, but hardly new types of words.  In the same way new sentences are being constantly created, but always on strictly traditional lines.  The enlarged sentence, however, allows as a rule of considerable freedom in the handling of what may be called “unessential” parts.  It is this margin of freedom which gives us the opportunity of individual style.