The conjunctions of these Planets among themselves, are called Grand Conjunctions on account of two most powerful rea-sons—namely, because they occur more rarely than the conjunc-tions of the other Planets, and because they produce greater effects on these sublunar things. The first reason is ccrtain to be sure, as is established by the Tables of Motions. But the second, some astrologers try to prove from the histories of principal events of the World, which they strive to apply to these conjunctions. And indeed, if we were to consider that Saturn and Jupiter also have their own systems, or satellites, like the Sun, it cannot be denied that, at least after the Sun, Saturn and Jupiter arc more so than the rest of [the Planets] of great virtue and authority in the World; and consequently, their conjunctions, squares, and oppositions can arouse great and also universal changes in sublunar things.

Therefore, since the conjunctions among themselves of these three, Saturn, Jupiter, and Mars, are famous among astrologers, even though we cannot crcct cclcstial charts for the moments of these, on account of their slow diurnal motion[1], especially when they are located around their stations[2]; nevertheless, we shall pro-pose some things here that must be noted about those conjunc-tions, which will also lead to establishing a more certain forecast from them.

Therefore, of those mutual conjunctions, one is said to be a Grand Conjunction in which those three planets are conjoined with themselves, which very rarely happens[3]. A Great Conjunction is one in which only Saturn and Jupiter [arc conjoined]. A Medium Conjunction is one in which only Mars and Jupiter [are con-joined][4]. But a Minimal Conjunction is one in which only Mars and Saturn comc together, for these arc the most frequent of all.[5]

But according to others, the Grand Conjunction is called the one in which Saturn and Jupiter are conjoined in a sign of absolutely contrary nature to the one in which the last preceding conjunction [occurred]. As, if their preceding conjunction was in a water sign, and the [conjunction] immediately following was in a fire sign, that is said to be a Grand Conjunction.1 The Medium [Conjunction] is one in which Saturn and Jupiter are conjoined in a sign partly of the same nature and partly of a nature contrary to the one in which their last preceding conjunction occurred. As if the preceding conjunction of Saturn and Jupiter wras in an air sign, and immediately following the conjunction was made in a fire sign. Finally, the Minimal conjunction is one in which these same Planets arc conjoined in a sign of the same nature as the one in which there last preceding conjunction occurred. As, if the preceding conjunction was in Sagittarius, and the one immediately following was in Leo, which signs are of the same fiery nature.

Whcncc it is plain that those astrologers only look at Saturn and Jupiter for the Grand Conjunctions. However, their Minimal Con-junctions occur [on the average] in 19 years and around 319 days according to the mean motions of those Planets, as Origanus chose from the Prutenic Tables. The Medium Conjunctions in 198 years and around 265 days.3 But the [very] Greatest Conjunction in 794 years and around 331 days.4 But even if both appellations should be lacking in their own reasons; nevertheless, the previous one seems to me to be more natural and truer. Both bccausc in the latter only Saturn and Jupiter are taken into account, with Mars excluded, for the greatest effects are with Jupiter or Saturn, or both of them, very powerful. And bccausc the first conjunction of Saturn and Jupiter that occurred, either at the creation of the World or after that, could not be said to be the Greatest, the Medium, or the Minimal by reason of the signs, since it was the first conjunction, and since no other one preceded the first conjunction. And only those that follow can be so called, by comparison with the one next preceding.

Besides, about these Great Conjunctions, three things must be noted from the outset. First, because the effects attributed to those conjunctions arc not produced by the mean conjunctions of those Planets—that is by those calculated according to their mean mo-tions—but only from their true conjunctions—that is those that arc completed according to their true motions[6]. And because, as we have already said elsewhere, the mean motions and the mean placcs of the Planets arc only fictitious things, and therefore of no real and active virtue, but only one contrived by astronomers lor finding the true motions and the true placcs of the Planets in the Primum Mobile with rcspcct to us, whcncc they arc perceived to act upon us, and not from their mean [places] where they are not [loeated] with rcspcct to us.

And finally, not only in other universal constitutions but also in the nativities of men, the mean places of the Planets arc not noticed for the causes of effects, but only the true places—both in directions and also in transits. For the mean placcs of the Planets arc only related to the center of the orbit of the Planet, in which the Earth is not [located]. And hence no light error can happen—cer-tainly, because the conjunction [calculatcd] according to the mean motions is in one sign, and that according to the true motions may be in another sign and under the rulcrship of another Planet. And in this, many astrologers who attach the history of things done in the World to those conjunctions were able to be deceived by having only taken into account the mean [conjunctions], and not the true ones.

Second. The conjunctions of Saturn, Jupiter, and Mars among themselves act on sublunar things in two ways: certainly, elementally, having taken into account the proper elemental natures of the Planets that are conjoined and the sign in which the conjunction is locatcd; and influentially, having taken into account the proper in-fluences of those Planets and the sign; and both of those natures must be noted with regard to the elements, and any mixture, both imperfect, such as meteors, and pcrfcct—namely minerals, vegetables, and animals.

Third. The conjunctions of Saturn and Jupiter, the Planets with satellites, are more effective nd produce greater effects, than the conjunctions of Saturn and Mars, or Jupiter and Mars, especially when they arc made in signs of an absolutely contrary nature to those in which the immediately preceding conjunctions of those Planets were made.