I got a very interesting question today. "On page 641 of Lilly's Christian astrology, chapter CLIIII, whether or not adversaries shall be overcome. He states, 'the lord of the seventh possessing the tenth or the lord of the tenth possessing the seventh, the native shall overcome his enemies. The lord of the twelfth in the tenth, or the lord of the tenth in the twelfth argues the same.'"
Does he mean the same thing by the lord of a house possessing another house as he means by the lord of a house being in another house? Or are these two distinctly different set of directions. What does he mean by the term possessing? Very good question and not one that I had an immediate answer to. Let's look at more uses of possession.
Lilly at Christian Astrology page 36, "That if on the Cusp of the tenth house you find the Signe Aries, then on the Cusp of the fourth the Signe Libra; and look what degree and minute of possesseth the Signe of the tenth house, the same degree and minute of the opposite Signe must be placed on the Cusp of the fourth house"
Lilly at Christian Astrology page 206, "[Tenants, good or ill.] If an Infortune possesse the Ascendant, the Tenants or Occupants are ill, deceitfull and unwilling the goodnesse of the ground should be discovered: if a Fortune be in the Ascendant judge the contrary, viz. the Tenants are honest men..."
Lilly at Christian Astrology page 230 "but if a fixed Signe possesse the Ascendant or 5th house, or any moveable Signes, and the Sun and Moon be therein, viz. either in fixed or moveable Signes, and in the 5th or 1st house, it’s a certain argument the Woman is with child but with one:"
Lilly at Christian Astrology page 239 "South Node also possesseth the Ascendant; a strong argument of barrennesse" [South Node is rising]
Lilly at Christian Astrology page 264, "If the Significator be in the middle of the Signe, the middle part of the Member is distressed, and so the lower part of the Member, when the Significator possesseth the lower degrees of the Signe."
Lilly at Christian Astrology page 267, "I usually observe, who is the Lord of the Ascendant, and which of the benevolent Planets he is in aspect with, and how many degrees there are distant betwixt them, in what house they both are in, viz. whether Angles, Succedant, Cadent, what Signe they possesse, whether Moveable, Fixed or Common"
Lilly at Christian Astrology page 422 "If in this house good Planets have either government, or are in possession thereof, or aspect the same without the testimonies of the Infortunes, it signifieth good, or is an argument thereof in all questions concerning this house" [9th house]
Lilly at Christian Astrology page 550 says, "If the Lord of the ascendant is beheld by no Planet partilly, judge by that mediety of the signe which the Almuten doth not occupie or possesse."
Lilly at Christian Astrology page 580-1, "Briefly, let him consider whether the Significator be happy or unhappy, secondly, the Signe he occupies: thirdly, the Infortune that afflicts the Significator: fourthly, the Signe he possesseth."
Ok, I should say at the outset that Lilly and his 17th century contemporaries were not always consistent in their use of terminology, jargon and terms of art. House, for example, is confusing because sometimes it means sign and sometimes it means one of the 12 houses.
Possessing definitely seems confusing! There does seem to be a tendency to use the term possessing with signs. This can be used of a sign possessing a cusp, which means that sign is on the cusp. More frequently we see a planet possessing a sign, which generally seems to be used to mean that the planet is in the sign. What is very confusing is that Lilly on several occasions contrasts occupying a sign with possessing it.
It is interesting to just considering the term possess
1 a : to have and hold as property : own b : to have as an attribute, knowledge, or skill
2 a : to seize and take control of : take into one's possession b : to enter into and control firmly : dominate
So to posses is to have ownership of something, but also has a sense of presence, of entering into and even of physically holding.
So we can see how possess could plausibly be applied either to house or sign rulership and simultaneously to emplacement in a house or sign. And in fact, house rulership and house placement both show the involvement of a planet, node, etc. with the affairs of that house.
So very interesting question and another example of the need to flexibility and tolerance of ambiguity in our traditional sources.