Co-Significators use

1
Hello,

The use of the planetary co-significators (chaldean order of the planets and their joy) is really not clear in my mind. Lilly names them when he describes the houses. But how are we to use them in practical delineation of a chart?

For some planets it seems clear (Mercury and Moon for the mind, where they have their joy in the first and third houses), but for other I can not understand.
Regards,
François CARRIÈRE