Most people will use this diagram to compare their zodiac sign to the sign of a lover or friend. While this can be useful, one must be aware that these are only general remarks on the nature of sign compatibility. It is not specific for Sun-sign comparisons. The table can be used for comparing any factors in the horoscope; Ascendants, Suns, Moons and planets. And what is more, the most useful comparisons are normally those between different planets, for example one partner's Sun-sign and one partner's Moon-sign. Here is the real treasure of astrological compatibility. Still, the diagram is a flexible tool, useful for any brief comparison of sign qualities.
Start from the left at the first sign of the match, and simply follow the row to the right to find sign number two and the symbol that represents the relationship. Then read below the diagram.
This combination doesn't need much explanation. People who share the same sign (or Moonsign) have no trouble connecting or understanding one another, but will scarcely thrill each other with the tingle of the unknown either. However, two people sharing different planets or points (especially Sun-Moon or Sun-Ascendant) in the same sign is much more significant. This is always a sign of much instinctive attraction and rewarding compatibility. When it is only identical Sun signs, it depends on other factors in the horoscope and also which signs we are talking about. Some get along easier than others. Often same-sign relationships result in passivity and boredom.
The classic image of "opposites attract" can often be found between signs that oppose each other in the zodiac, but the matter is usually quite complicated. With opposing signs, the similarities are much more evident than people think. The relating is a matter of constant mirroring of each other; complementing but also repelling. Quite obviously, the result can be highly productive and affectionate, but also soaked in jealousy and balancing at the edge of a great fall. People showing much opposing planetary energies always have a lot offer to each other, and the best promise of the exchange is heightened perspective and a fated bond of souls. Worst: hatred, intolerance.
Signs in trine relationship belong to the same element - fire, earth, water or air. This creates a basic similarity in responding to things, and a temperamental affinity that while not identical (and probably because of this) promises much intuitive and sympathetic rapport between the individuals. Lovers as well as friends harmonize without much effort, and tend to find similar things important. It is as if the relationship itself radiates a sense of grace, a cosmic idea of form and well-being. The downside to the trine combination may actually be too much tolerance and not enough drive for individual growth.
Signs in square relationship have an ambivalent attitude towards each other. On the one hand they are very aware of each other's presence, and frequently communicate very well. Friendships are common between people with squaring planets because of the dynamic nature of the interaction. However, it is often too unstable and provoking to be a pleasant exchange. Especially between lovers, where it can be a heated affair, but at the risk of constant arguing that leaves bitterness and irritation behind. Perhaps it is the interaction that requires the most rearrangement and compromise to work, and for the persons to simply tolerate each other. A successful bond can be strong, however.
The "quincunx" relationship between signs is an interesting but problematic combination. Basically it relates signs that share virtually nothing in general. By this testament only, the result could be ships that pass in the night. Still, there is an aura of mystery and fascination with this interaction, as one partner seemingly possesses qualities completely absent in the other, qualities that cannot be expressed at the same time. Some astrologers have associated this angle with a subtle sexual allure, and it seems likely in view of the perplexing attraction that we all sometimes feel strongly without being able to motivate it. Nonetheless, any strong quincunx match requires a great deal of awareness to actually function.
Signs in sextile are of different but compatible elements, and their merging is usually natural and unguarded. In many respects this interchange is the ideal for partnerships in which one side adds just enough of what the other lacks, not least in friendships or professional/platonic exchanges. However, while it brings comfort and security, this is not the most magnetic and exciting match when it comes to romantic/sexual contacts. Still it is a solid foundation to lean against, and when different planets sextile each other between two partners' horoscope, it's a sign of great understanding and pleasant attraction.
Semi-sextile signs are positioned next to each other on the zodiac wheel. This creates an uncertain response that is sometimes tinged with competition or jealousy. The point is that bordering signs represent a process of learning and development, of leaving things behind and making progress. For the preceding sign, the partner may seem to display qualities that they themselves lack or would secretly want more of, and hence they might find the partner annoying or arrogant. For the latter sign, the partner seems somewhat veiled in mystery, or appears to cling to attitudes they believe to be unnecessary or obscure. This is all quite abstract, but there is a certain evolving and bonding with the relationship, in itself both mildly disturbing and captivating.