Rhys is a short, sturdy Welsh name traditionally linked to ardor or enthusiasm -- passion in the sense of drive rather than volatility. It's often chosen for its brevity as much as its meaning, a name that doesn't need embellishment to carry its intensity.
If possible, the planets must be reinforced with a fixed star from the same nature, because it concentrates the power of the influx and the duration of the work. - Picatrix (Andalusia, ~1000.AD)