In view of the close relation between illuminating boundaries of convex bodies and Hadwiger's covering conjecture
it is proved that parallel light beams illuminating the boundary of a convex body can be uniformly compressed. Based on this
a new proof
without using induction
is given to show that the least number of smaller homothetic copies of a convex body needed to cover this convex body is equal to the least number of parallel light sources needed to illuminate its boundary.