I had a good question recently from a student who asked me what the significance of partile versus platic (or platick) aspects. First, what are they? Here's Lilly's explanation from Christian Astrology at pages 106-7:
"There is also a Partill or Platick aspect: Partill aspect is when two Planets are exactly so many degrees from each other as make a perfect aspect: as if Mercury be in nine degrees of Aries, and Jupiter in nine degrees of Leo, this is a Partill Trine aspect: So Sun in one degree of Taurus, and Moon in one degree of Cancer, make a Partill Sextile, and this is a strong sign or argument for performance of anything, or that the matter is neer hand concluded when the aspect is so partill, and signifies good; and it's as much a sign of present evill when mischief is threatened."
"A Platick Aspect is that which admits of the Orbs or Rayes of two Planets that signifie any matter: As if Venus be in the tenth degree of Taurus, and Saturn in eighteen degrees of Virgo, here Venus hath a Platick Trine, or is in a Platick Trine of Saturn, because she is within the Moity of both their Orbs; for the Moity of Saturn his Rayes or Orbs is five, and of Venus 4, and the distance betwixt them and their perfect aspect is eight degrees..."
So, partile does not mean less than a degree away, it means that the planets are both in the same degree of the sign they are in. Ok, Lilly mentions partile and platick, I have students learn it in the course, but what does it mean?
This raises the issue of what I call "fossilized" technique in traditional astrology. Traditional astrology, not surprisingly, is very respectful of tradition and what has been passed down from earlier practitioners. Traditional astrologers did not simply toss out technique when they didn't understand it or didn't use it. Arabic astrology, which is the basis of traditional European astrology, was much more complex and so there are lots of things the Arabic astrologers used, which the medieval and Renaissance astrologers knew about and might even mention, but then didn't use.
Partile and platic or platick aspects are one such fossilized technique. Lilly mentions them, but I don't think he ever really uses them in a delineation. What I would say is that with applying aspects the closer you get the stronger, or the quicker, so clearly a partile aspect is very strong or very quick.
Let me mention another interesting thing about separating aspects of less than a degree similar but not the same as partile/platick, this is from Bonatti's 146 Considerations
"17. The 17th Consideration, is to view whether the Planet that is Significator, be safe and prosperous, that is free from any affliction from the Infortunes; and one of the Fortunes casts his beams or light on the beams of such Significator; for then shall that Planet be said to be safe and guarded till the Fortune is passed by the space of one minute, and signifies the perfection of the thing. But after he has passed him one minute, it will not be perfected or accomplished; for it only raises hopes; as (we said) the malevolent in the like case could do nothing, but create fear. Yet is such a hope as the Querent will believe and fancy himself as it were certain; yet not without something of doubt;
as for example, A Question is proposed of some weighty and difficult business, whether it will be done and brought to pass or not? And 17 degrees of Scorpio Ascends, and Mars is 12 degrees 13 minutes of Taurus, and Venus in 12 degrees and 14 minutes of Capricorn, so that Venus is joined to Mars by a Trine, and receives him in her House, who likewise receives her in his Exaltation; so that the Querent thinks, and all others concerned verily believe, that it would be accomplished by that aspect of perfect friendship; in which flattering hopes they continue till Venus hath passed the Aspect of Mars one whole degree; but at last the business comes to just nothing at all, because Venus was past Mars one minute at the time of the question proposed. Yet may a thing possibly in such a case be brought to pass, but not without extraordinary labour and trouble. "
I've seen situations where we have a separating aspect of less than a degree, and the asked for thing was perfected, but with a huge hassle.
So as traditional astrologers, we frequently encounter technique that we don't use or often don't fully understand, but just because we don't understand it, we don't simply toss it out. We respect the tradition and often, when we delve deeper, we find for ourselves the wisdom and deep experience of our predecessors. This is part of what it means to be a true traditional astrologer as opposed to a modern astrologer using dribs and drabs of traditional technique on an unconsciously modern overall methodology.