Below is a classic periodic sentence from Martin Luther King, Jr.'s "Letter from Birmingham Jail." In this 300-word plus sentence, King piles up dependent clauses, each giving specific examples that show the reader the kind of injustice he was fighting. When we discuss the sentence in class, I try to get students to see that in this sentence form follows function: As King provides example after example, the reader must "wait" just as blacks had to wait for justice.
Perhaps it is easy for those who have never felt the stinging darts of segregation to say, "Wait." But when you have seen vicious mobs lynch your mothers and fathers at will and drown your sisters and brothers at whim; when you have seen hate filled policemen curse, kick and even kill your black brothers and sisters; when you see the vast majority of your twenty million Negro brothers smothering in an airtight cage of poverty in the midst of an affluent society; when you suddenly find your tongue twisted and your speech stammering as you seek to explain to your six year old daughter why she can't go to the public amusement park that has just been advertised on television, and see tears welling up in her eyes when she is told that Funtown is closed to colored children, and see ominous clouds of inferiority beginning to form in her little mental sky, and see her beginning to distort her personality by developing an unconscious bitterness toward white people; when you have to concoct an answer for a five year old son who is asking: "Daddy, why do white people treat colored people so mean?"; when you take a cross county drive and find it necessary to sleep night after night in the uncomfortable corners of your automobile because no motel will accept you; when you are humiliated day in and day out by nagging signs reading "white" and "colored"; when your first name becomes "nigger," your middle name becomes "boy" (however old you are) and your last name becomes "John," and your wife and mother are never given the respected title "Mrs."; when you are harried by day and haunted by night by the fact that you are a Negro, living constantly at tiptoe stance, never quite knowing what to expect next, and are plagued with inner fears and outer resentments; when you are forever fighting a degenerating sense of "nobodiness"--then you will understand why we find it difficult to wait.
Using King's sentence as a model, I created my own periodic sentence made up of a pile of dependent clauses. It certainly not as monumental or memorable as King's, but as the father of a teen, it was cathartic. It also features a hyphenated modifier near the end:
If you clean your filthy, festering pit of a bedroom, remembering to fold your clothes, make your bed, vacuum the floor; if you take out the garbage that you’ve neglected for the past week; if you complete your overdue English homework on the stylistic features of the periodic sentence; if you take the dog for a walk and clean out the cat’s litter box; if you are nice to your little brother for once; if you stop giving me those I-can’t-believe-that-anyone-would-dare-ask-me-to-pick-up-my-sweaty-T-shirt-from-the-kitchen-floor looks, maybe you can go to the movies.