The astrological zodiac is arranged in such a way that as we move from one sign to another all of the important characteristics of the sign change in dramatic ways. This is true particularly when we look at the sign qualities, - their polarities, modes and elements.
Thus, the polarities of masculine and feminine, the modes of cardinal, fixed and mutable, and also the elements of fire, earth, air and water, never repeat themselves in successive signs. While this is not a problem in most areas of astrology, and in fact helps us to more clearly understand the boundaries as we move from one sign to another, it does come into play quite dramatically, when we think of out of sign aspects.
We are accustomed to seeing conjunctions for example, (two planets within nine degrees of each other) usually within the same zodiac sign. As such, the interpretation of such an aspect is easily arrived at inasmuch as each planet cooperatively enhances the other with the strength of the sign they share.
What happens, however, when we see a very high degree planet in one sign forming a conjunction with a very low degree planet in the following sign. Thus a high degree planet in Aries could form an out of sign conjunction with a low degree planet in Taurus.
For one thing, because the energies of both planets are being modified in different ways because of the two different signs they are in, the individual feels a complexity quite different than conjunctions that occur within the same sign.
While the planets still work cooperatively because they are a conjunction, the individual has to work a little harder to combine the substance of what these two planets are offering. In the example we mentioned of Aries and Taurus, the person would have to learn to combine the fiery, masculine, cardinality of Aries with the earthy, feminine, fixed qualities of Taurus.
Two factors come into this that are very important. First, the outermost planet (the larger, slower moving planet) holds influence over the innermost planet. This happens because the outermost planet always has a slower transit and progression effect, often staying in the same sign for years at a time, thus weighing more on the individual with important life lessons that have to be learned.
If we saw a Saturn in Aries forming a conjunction with Mercury in Pisces. The fiery,cardinal, masculine qualities of Aries working on the planet Saturn would hold influence over the watery, mutable, feminine qualities of Pisces modifying Mercury.
Breaking this down to understandable language, the individuals need (Saturn), to break barriers and experience new beginnings (fiery cardinal and masculine qualities of Aries) that seem to promise a practical outcome would be helpful in positively influencing the timidity of the Pisces Mercury so that its changeable mutability, and watery feminine qualities could find purpose in its creative expression.
It takes a little more to understand these out of sign conjunctions, because they seem to always involve discordant energies that a lazy individual would rather not deal with. However, they offer unthought of possibilities for the person to transcend the mundane.
There is a second factor in these very special conjunctions that comes from the fact that a high degree planet is always more evolved than a low degree planet. Thus, the planet near the end of the sign, seems to hold within it, more knowledge and perhaps soul experiences (maybe even coming from past lives) that the low degree of the planet in the next sign that it is conjunct with cannot even imagine by itself. The low degree planet is often thought of as being more primitive, and basic, in earlier lifetime stages of development than the higher degree planet.
This really gets interesting when we study both of these factors together. If the higher degree planet is Saturn (the planet of age and wisdom and karmic lessons), and the lower degree planet is Mercury (the planet of thought and expression) then it can easily be concluded that the Saturn is influencing the Mercury towards sober, mature thought. But, what happens when these planets show up the other way around?
If Mars is in a higher degree than Saturn as they form a conjunction, then it has to be concluded that Mars is more evolved and the individual's propensity towards action is more knowing than their sense of practicality and planning. Combine these factors with the Sign qualities of polarity, mode and element of both planets, and there you have it.
Remember also, that most of the time, transits will effect the higher degree planet first (as it is in the earlier of the two signs) thus giving the individual time to get in touch with all they have learned in past lives and accumulated in their soul in order to have enough wisdom to deal with the transit in the best way possible as it completes itself over both planets. See how easy the universe makes it for us? If only we would listen!