Ten Things That Come in Groups of Seven

"All seven and we'll watch them fall," Prince once said, "They stand in the way of love and we will smoke them all." But Prince was already well on his way to becoming a raving lunatic. A brilliant one, sure, but a raving lunatic all the same.

Still, there's a reason he named his song "7" and not, say, "11". Seven is a 'signifying' number, filled with all kinds of supernatural significance. But it's awkward and lopsided; it's the first prime number to really feel like one, defying all attempts to comfortably break it up into smaller pieces. Additionally, if you need proof that mathematicians are insane, seven is a 'happy number', it's the base of the 7-aliquot tree, and n = 7 is the first natural number for which the next statement does not hold: "Two nilpotent endomorphisms from Cⁿ with the same minimal polynomial and the same rank are similar." Er, sure. Whatever.

More importantly, there are many things that come in groups of seven. Like these.

1.	THE SEVEN WONDERS OF THE WORLD: The patron saint of websites such as this one, Herodotus (484 - 425 BCE) would be amazed at how his best-of list, scrawled perhaps on a placemat over a pint or two with drinking buddy Callimachus of Cyrene, has survived 2500 years despite being a woefully adequate list of by-now-forgotten oddities located int he eastern Mediterranean region (and thus as representative of the 'world' as baseball's 'World Series'). The truth is it hasn't really survived, both in that no manuscripts of the era exist, meaning we know the list only through hearsay, and in that the average person, if asked to name them, will confidently spout off a completely random list of seven places that will probably share only the Pyramids of Giza with the actual list. Mind you, that list (perhaps containing the Taj Mahal, the Great Wall of China, Stonehenge, those big heads on Easter Island...) will be superior to Herodotus' (the Mausowhat?).
2.	THE SEVEN DEADLY SINS: We have Brad Pitt and Kevin Spacey to thank for permanently turning this list into horror-show memories. But it's an odd list, really - the same religion that gives us 'all sins are equal in the eyes of the Lord' gives us a list of seven that are, well, superbad. Oh, there's also the Ten Commandments, which overlaps this particular list only slightly. I mean, it doesn't have sloth. Or gluttony.
3.	THE SEVEN DAYS OF THE WEEK: Where the day is based on the earth's rotation on its axis, the month is traditionally based on the moon's revolution around the earth, and the year is based on the earth's revolution around the sun, the week seems to be based on nothing more than superstitions about the number 'seven'. Not quite a quarter of a month, a week seems most closely connected to the Judeo-Christian creation myth. Yet seven-day weeks existed in other parts of the world too, in addition to all kinds of variants such as the ten-day week of the French Revolution, the five- and six-day weeks in the early years of the USSR, or the five-day week still used in Indonesia, where (get this) it is used overlapping with the Gregorian seven-day week in 35-day cycles. Also of note is the eight-day week used in Liverpool in the mid-1960s.
4.	THE SEVEN HILLS OF ROME: Here's a curiosity: The city of Rome attaches significance to the fact that it was built on seven hills. People talk about the 'seven hills of Rome', all east of the river Tiber, in the heart of Rome. Now, Rome is a city that likes its creation myths: recall it was founded by a pair of twins that were raised by a wolf. But what's stranger is there are fully fifty-one cities that claim to be situated on seven hills, from world cities such as Barcelona, Istanbul, Jerusalem, Mecca, Moscow and Tehran to humbler world-city aspirants such as Dunedin, New Zealand; Kampala, Uganda; Thiruvananthapuram, India; and Yonkers, USA. There doesn't seem to be anything much impressive about having eight hills in your city.
5.	THE PLEIADES: The Pleiades of Greek mythology are a group of seven nymphs also called 'the Seven Sisters', since they were all born to Atlas (who seems to have been quite prolific). In sculpture and art, they tend to dance a lot and tend to be naked a lot. Zeus had his way with three of them, and Poseidon with two. Clearly they got around. So Orion, the big bad guy of the story, decided to hunt them down after daddy Atlas got stuck holding the earth and Zeus decided to protect them by turning them in to stars, which is why a star cluster exists in the night sky called the 'Pleiades'. Orion's up there too, not all that much of a hunter after all, it would seem.
6.	THE SEVEN SAMURAI: Akira Kurosawa's three-and-a-half-hour 1954 samurai epic has to go down as one of history's most-praised films. A cornerstone of the Japanese film industry and of the action movie, it was a huge success domestically and, rare for the era, internationally. So well-received was it internationally that it was immediately nicked and rewritten in Hollywood as a western, The Magnificent Seven, which was still a huge success, both at the box office and in the critics' columns.
7.	THE GROUP OF SEVEN: I don't mean the "G7", which is what the G8 used to be before there were eight of them and can still be played on a guitar in the position 320001. I mean the 'Group of Seven', a group of Canadian artists who no Canadian can remember any of the names of. They painted landscapes of Canadian trees, grass, rver and leaves, and are famous in the government-endorsed way most 'famous Canadians' are famous. Tommy Thompson and Emily Carr, two Canadian landscape artists from the era people actually can name, weren't part of the Group of Seven.
8.	THE HARRY POTTER SERIES: J.K. Rowling, currently unemployed, must now be banging her head against the wall regretting her early rash decision to limit her record-breakingly successful Harry Potter epic to only seven volumes. Warner Brothers might bang her head against the wall too, though at least they've managed to squeeze out an eighth movie. Seven volumes for seven years of Hogwarts, and there are several other sevens popping up in Rowling's magical world. Most obviously, it's the number of horcruxes Voldemort makes. Though I guess technically that's a spoiler.
9.	THE SEVEN WORDS YOU CAN'T SAY ON TELEVISION: George Carlin has gone down in infamy largely for swearing a lot on stage. In his defence, the infamous routine, "Seven Words You Can't Say on Television", is not merely about the shock value of those very words: it's more a discussion about why those words are so shocking, and it's pretty intelligent entertainment. The list is imperfect - 'tits' and 'piss' are relatively tame, and certain worse words are absent from it. But I guess that's the point - language evolves, and our 'dirty words' evolve right along with it. Oh, and I should point out this really refers to broadcast television. If it's a cable-only channel, everything goes.
10.	THE SEVEN CHAKRAS: In short, the chakras are seven areas of the body that, in Hinduism, are... well, energy..., um, places... and... Okay. I give up. I've read explanations of chakras over and over again, and I understand nothing. It's something connected with Hinduism, it's got all kinds of cool pseudo-psychedelic illustrations like the one here, and... well, that's is. I can list the seven chakras, if you want: the first is in the ovaries or prostate, the second in the last bone of the spinal cord, the third in the navel, the fourth in the heart, the fifth in the throat or neck, the sixth in the pineal gland (whatever that is) and the seventh on the top of the head. You know, it's no sillier than the seven deadly sins.