Witcher Wiki

Intersections are places from which mages can draw the Force. These intersections are located by "feeling" their presence so those not magically inclined would never notice them. Yennefer describes the feeling to Ciri as a slight cramping in the ring finger, extending downward. Cats like sleeping and resting on intersections, so their presence often signifies an intersection.

Apart from dragons, cats are the only creatures known to absorb magical energy, but no one knows what they do with it.