Dexter literally means ‘of the right’ and refers
to something on the right hand side; sinister means ‘of the left’ and refers to
something on the left hand side. According to Pythagorean principles, movement
towards the right is more natural and direct than movement towards the left
(hence the term ‘righteous’ or the negative undertones given to the word
‘sinister’ generally). This partly recognises the influence of diurnal motion
(by which planets move from left to right), and the fact that in any cycle
between two planets, the faster moving planet will cast its aspect to the other
on the right hand side whilst the cycle is waxing (suggesting growth and
vigour), and to the left hand side when the cycle is waning (suggesting
retirement and weakness). A ‘dexter aspect’ is therefore said to be more
forceful and effective than a sinister one. Dexter aspects are formed in
keeping with diurnal revolution (for example, a planet in Pisces applying to a
sextile of a planet in Capricorn); sinister aspects are formed against diurnal
revolution (for example, a planet in Pisces making a sextile to a planet in Taurus).
