What is the Ascendant?
The Ascendant is the name given to the zodiacal sign found on the beginning (or the cusp) of the 1^st House which traditional astrologers called the House of Life. In a horoscope, its location corresponds to the 9 o'clock position on a clock face. (Figure 1) The particular sign a person has on their Ascendant is based not only on their birth date but also their birth time. The date of birth gives us only the position of the planets on that day. Without the time of birth, we cannot calculate and know a person's Ascendant. This is why the time of birth is so very important for the Astrologer.

Astronomically, the Ascendant is the name given to that point where the Zodiac intersects with the eastern point of the local horizon. In antiquity, the Greeks called this point the horoskópos or horoscope which later on came to be the term associated with the chart as a whole.

What is its importance?
The Ascendant is the most important consideration in the horoscope as it is  the body, the physical constitution with its natural predisposition. It is also the psychological organization of the person, the mask of habitual reactions that stand between the outside environment and the internal and subjective private world of a person.  To stress the importance of its value, Zoltan Mason taught his students that it is about 80% of the horoscope!

          Figure 1 - The Ascendant

From the viewpoint of observation, the Ascendant describes the range of reactions by the person to the environment. A person will respond to and be characterized by the affairs associated with the zodiacal sign on the Ascendant. It will be those affairs that will always be in the back of the person's head; it is their ambience.

If as in  our example,  the person has Cancer rising, which corresponds to the Zodiac's Fourth Sign, we know automatically that the person will somehow be connected with the home, parents and family and the past in general, as the sign Cancer is connected with these affairs. As a consequence, these affairs are always going to be important life long to the person with Cancer rising. The person will respond to and behave according to the affairs connected with the Fourth Sign.

Thus, through the nature of the zodiacal sign on the Ascendant at birth, a person is naturally inclined to react towards the environment in accordance to the sign's characteristic  nature.