T-Square
The T-Square is an aspect figure which is formed when two planets in opposition (i.e. 180 degrees apart) are both squared by a third planet. Both these aspects are considered to be so-called "hard" or "disharmonious" aspects, and the T-Square intensifies this quality in both which makes it a very challenging aspect ("Disharmonious Aspect"). The third planet is the focal point of the figure and could be said to carry the tension of the two planets that stand in opposition. It is also at the midpoint of these planets. However, the tension between the two planets in opposition is also raised by the third planet forming a square to both.
The intensity with which the themes associated with the T-Square are felt by the individual concerned means that they cannot be ignored, forcing the person to take some kind of action. For this reason, there is great potential inherent in this aspect figure. Another planet standing in sextile and trine to the two planets in opposition indicates how the tension can be relieved.