What is in a trine?
What is in a trine? Well, three planets at least, equally spaced (within an acceptable orb or range), each point of the triangle being (most often) in a signs that have the same element (fire, earth, air, water). Think about what this all means.
The trine's planets tend to have the same expressional qualities due to their signs element focus being the same. Almost any aspect to one of the planets will have some kind of aspect relationship to the other two planets -- this creates complications. The aspectual complications will tend to be overridden by the trine itself -- trines tend to interact with each member in an almost automatic mode. In other words, its easier to express the trine energy in every case than use/apply one of the other aspect patterns.
Guess what happens when a transiting planet makes an opposition or conjunction to any one of the three planets? It triggers the trine, reinforcing the use and reliance upon the trine energy. Trines tend to be habit forming, you use the energy a certain way -- but you seldom grow or change from that experience. This is why squares and t-squares are to valuable to one's growth and development -- they create a conflict, a challenge that drives us to use whatever is thrown at us.
Now, you also have to look at who makes up a trine! Are all of the planets involved compatible, is one of them antagonistic to the other two, is one stronger due to its house/sign placement or aspect patterns to a planet outside of the trine pattern?
What is in a trine? Good food for thought, a good learning opportunity with this question. Dave