Mystery of the Masquerade

Most astrologers would agree with Molly Hall's explanation of the meaning of our ascendant/rising sign:
(Snip from About.com HERE)

The Rising sign is known as the mask of the persona, and the first impression we make on those we meet. It could be said that the qualities of the sign that was rising on the eastern horizon imprints on the outer self as we emerge into the world. After that, each time we encounter a new situation or person, this is the "face" we reveal.

If you've ever been puzzled by how others describe you, it could be that they've encountered the Rising sign qualities. It's the image facing outward, and might not be how you see yourself at all. It is the front door of the self, but as much a part of the personality as the Sun sign.

The Rising sign deals with First House issues like appearance and personality, and can even influence physical characteristics. If the Sun is the core self, taking action in the world, the Rising sign is the vehicle with which to do it.

C.E.O. Carter, well-respected 20th century British astrologer, had some less common ideas to share (see HERE) ~~

On the Ascendant as a Mask:
Recently we have heard a good deal to the effect that the rising sign, and in particular the ascending degree, is a mask which the native wears before the world but which conceals his true self. As I have stated in the Lodge, this proposition does not seem self-evidently true. It seems to derive from the practice, in Alan Leo times, of correlating the Sun with the 'individuality' and the Moon with the 'personality', using these words in their well-known theosophical senses. 'Personality' is further derived from the Latin persona = something one makes a noise through, hence a mask such as actors were wont to wear, with a wide-open mouth. Then, apparently, this idea of a mask was transferred to the ascending sign...

I suggest that it is not the rising, but the setting degree, that is more truly a mask, for it is through this that we contact other people, and unless we have very strong personalities (in the usual, not the theosophical, sense) we do modify our demeanour according to the man or woman who confronts us..." [From an Editorial in The Astrologer's Quarterly, September 1951]

Below is a list of the zodiac signs with their opposites, as rising and setting i.e. ascendant/descendant signs:

When Aries is rising, Libra is setting
Taurus rising - Scorpio setting
Gemini rising - Sagittarius setting
Cancer rising - Capricorn setting
Leo rising - Aquarius setting
Virgo rising - Pisces setting
Libra rising - Aries setting
Scorpio rising - Taurus setting
Sagittarius rising - Gemini setting
Capricorn rising - Cancer setting
Aquarius rising - Leo setting
Pisces rising - Virgo setting.

Mr.Carter's theory makes sense to me. Other astrologers have proposed that the descendant indicates "what we need", in a partner, or in life. I like Carter's idea much better. It seems to work in all the charts I've been able to check so far. Admittedly this is not a large number, because times of birth have been elusive for many of my close connections throughout life. It's a stumbling block for people in Britain where times of birth have not always been routinely recorded.

My own descendant is in Capricorn. I've been told more than once that I come over as a solidly, reliable Capricorn-type. This makes my revolutionary Aquarian Sun bristle, and my Aries Moon put up its fists! As Mercury lies in Capricorn in my chart I've usually blamed the impression I seem to give on that placement. There's also the fact of Saturn being traditional ruler of Aquarius to consider in my case, so I mightn't be a good example. I do doubt that the first impression I give is that of my rising sign, Cancer. I'm anything but motherly. I've never been a mother, never wished to be a mother in fact; I'm house-trained but hardly domesticated. I am ultra sensitive and sentimental/emotional, and in my youth I was shy (Cancerian traits) but few would perceive that from a casual meeting.

I tried Mr Carter's theory on my husband's chart. He has Leo ascending, Aquarius on the descendant. He has told me that when he was young he deliberately tried to be original and different, not to conform with the fads of his contemporaries - in the way he dressed, his hair style, his taste in music, the way he spoke. That clearly says Aquarius to me, not Leo. Matured now, less avant garde in most things, but still his Leo remains well hidden to outsiders, just a part of the mix of his real self, his natal Moon is in Leo too. When I first stumbled across him on the internet, the impression I had was of a school teacher or some such academically inclined mortal. It turned out that he wasn't, but his demeanor was definitely more Aquarius than Leo. His eldest daughter has a similar Leo ascendant, these remarks could apply equally to her.

Charles Carter's theory is something worth keeping in mind. What has to be kept in mind also, is that how we see someone else often says more about who we are than who they are! The plot thickens!