These are not weak aspects. An exact semisquare or sesquiquadrate is more important than a square that is several degrees out, and many traditional astrologers who have ignored these so-called minor aspects have missed out on important information.
– Robert Hand, Horoscope Symbols
In Aspects in Astrology: A Guide to Understanding Planetary Relationships in the Horoscope, Sue Tompkins writes about how sesquiquadrates show up in accident charts, representing a kind of unavoidable energy- energy that manifests concretely . Regarding natal charts she believes that this aspect demonstrates itself through outer events rather than inner psychology because of what she sees as the tendency for these aspects to be “more deeply buried.” She goes on to say,
I suggest that the reason why semi-squares and sesquiquadrates manifest so readily in terms of outward events is simply because of the greater unconsciousness of these aspects.
— Sue Tompkins, Aspects in Astrology
Both Hand and Tompkins describe sesquiquadrates as being an energy similar in expression to the square, but less intense.
If you have two planets that are square to each, like Moon square Saturn, then, you have a third planet that makes a sesquiquadrate to each of those planets, for example, Neptune, then what you have is a configuration called Thor’s Hammer, or The Fist of God.
