The sign that is on the eastern horizon at the moment of birth is called the Rising Sign or the Ascendant. The Ascendant marks the difference in temperament, disposition, physical appearance and personality of individuals. It is the lens through which everything else in the chart is focused or looked through, thus coloring the way we look at everything. People see us through our rising sign and we see the world through our rising sign.
The planets represent energies and cosmic forces that can be utilized in various ways. They are like the actors in a play. Houses represent the different spheres of life where these energies can be and are brought to bear, for better or for worse. If the planets are the actors in a play, then the houses represent the various settings in which the actors play out their roles (signs).
If the planets represent energies and cosmic forces that manifest in different ways, then the planetary aspects show how these energies and forces tend to act and react, one with another, if the will of the person is not brought into play to change them.