A Treatise on Astrology, Liber 536 by Aleister Crowley, 1917

Neptune and the other Planets

In that baser and narrower astrology which concerns itself solely with the material plane, Neptune appears as a malefic. One may go so far as to say that he seems more sinister and obscure a malefic than even Saturn. The reason for this is that he represents the influx of a spiritual element which cares nothing at all for the affairs of this earth. The other planets deal with the relative; they are commensurables; Neptune intrudes upon them as the absolute and incommensurable. He represents in life the effect of the squared circle and the double cube in mathematics. For those who are devoted to the spiritual he is, therefore, wholly good; for others wholly bad. He wrests them from serenity.

Conjunction generally means confusion, unless the natures of the conjoined planets be very harmonious. The conjunctions of Neptune are therefore ominous to the conjoined planet unless there be other support.

Opposition generally means conflict and exhaustion; both planets lose in force. The quartile aspect means attack ; both planets become more brutal. (This is not always necessarily bad: for example, Sun quartile Mars in a question of Health might seem a rude robustness.) The sextile aspect is friendly, bringing out the softer qualities of both planets.

The trine aspect resembles the alliance of two great kings. They mutually support and defend one another; the strength of both is brought out in its best form. This aspect is more important when the planets are large and slow-moving.

These remarks should be taken into consideration in the study of the following. For convenience and brevity the aspects have been classed simply as friendly and unfriendly; and they must be modified according to the map whose interpretation is demanded. The exact plane, on which the effect operates, depends of course upon the houses in which they are situated, or which they rule.