The essential dress is always a summer dress. Obviously there are cocktail dresses and evening dresses (those ridiculous, frequently monstrous creations worn by actresses at the Oscars), but none has the allure of the summer dress, which contains all the promise of summer itself. My personal favourite is a red silk shift dress with gold patterned panels at the sides which I bought for my wife in Vientiane, Laos, about 10 years ago; a decade later it's still going strong, its promise unbroken.
I am aware of the dangers of converting personal preferences into rules but, in the spirit of Wallace Stevens' poem "Notes toward a Supreme Fiction" ("It must be ..."), here are my thoughts on the perfect (summer) dress:
First, it must be sleeveless. Obviously. I announced this, years ago, to my wife. "But I have a dress with sleeves," she said.
"Which one is that?" I asked.
"The one with sleeves," she replied wittily. She might, more accurately, have said "the one plus sleeves," as sleeves are an add-on to a dress—an addition that serves to subtract from the total effect. A summer dress makes an important political statement about women's right to bare arms.
So less is more—but only to a degree. If the dress is very short then it is too obviously sexual. And then, because the wearer has to make sure that the dress is not too revealing, she is all the time having to pull it down or restrict her movements, thereby contradicting one of the essential purposes of the summer dress: absolute freedom of movement. (There is an interesting potential exception to this: the tennis dress is in some ways a sub-set of the summer dress but if it has to be accompanied by special underwear—underwear designed to be seen by the world at large—then the tennis dress stops being a summer dress and becomes purely a tennis dress. In short, it is possible to play tennis in a summer dress but it is not always possible to wear a tennis dress as a summer dress.)
A summer dress always looks best without tights or stockings. It is about limbs that are either tanned or in the process of becoming so. It is an advertisement for health and fitness (as such it is defiled by any association with cigarettes). The summer dress is only incidentally sexual; as such it is far sexier than the kind of fetish clobber or lingerie on offer in Agent Provocateur. Ideally it is even worn without make-up. In the context of ball gowns, where everything is artificial and heightened, make-up does not look out of place, but the summer dress makes anything but the most discreetly applied make-up look unnatural and unhealthy.
Although women wear high heels with summer dresses there is an essential contradiction between the freedom and lightness implied by the dress and the decorative, restrictive nature of the shoes. A summer dress looks best either with sneakers, sandals, flip-flops or, ideally, no shoes at all.
It does not require special treatment. It can be crammed into a duffel bag. It doesn't even have to fit perfectly.
Price is irrelevant. You can pay a lot but, equally, it can be the kind of thing you can pick up for next to nothing. This is appropriate because, in a sense, it is next to nothing, though it is also all-purpose: as mentioned, it works for tennis, but also hiking or cycling and it can then be worn to a party—no matter how glamorous—that same night. So a summer dress can serve as a cocktail dress but not vice-versa.