This is said to be the most powerful aspect, intensifying the effects of the involved planets mutually — and being a major point in the chart.
The sextile has been traditionally said to be similar in influence to the trine, but of less significance. It indicates ease of communication between the two elements involved, with compatibility and harmony between them, but only provides opportunity, requiring effort to gain its benefits.
The trine indicates harmony, and ease of expression, with the two elements reinforcing each other. The trine is a source of artistic and creative talent, which is innate. The nature of the trine is that of the fire signs (Aries to Leo and or Aries to Sagittarius) and is thus inspirational. The trine has been traditionally assumed to be extremely beneficial, providing ease even if undeserved, but it can be a 'line of least resistance' to a person of weak character. Too many trines are said to make a person weak and unable to cope with adversity.
As with the trine and the sextile, in the square, it is usually the outer or superior planet that has an effect on the inner or inferior one. Basically, the square's energy is similar to that of a trine but it is intensified to such an extent that the energy is said to be stressful. For example, Mercury square Saturn indicates practicality and prudence with thoughts and communication, concentrating on practical matters. It is also indicative of caution in planning and other mental tasks. However, the square between those planets indicates mental restraint, excessive censoring of communication and overemphasis on trivial details. It also indicates pessimism and a stilted and fearful approach to life. The square is said to indicate strain, tension, frustration, inhibitions, disruption and inner conflict. However, it can become a source of energy and activation to a person determined to overcome limitations, presenting challenges to achievement and an opportunity to develop strength of character.
Oppositions are said to be the second most powerful aspect. It resembles the conjunction although the difference between them is that the opposition causes exaggeration as it is not unifying like the conjunction but instead exalted. So the fact that the opposition creates a dynamic and exalted energy between the planets involved is not as clearly negative as for instance the square, but it can be indicative of tension, conflict or confrontation, due to the polarity between the two signs involved if not channeled constructively. If channeled constructively however the individual may use it as a creative and energetic power source.