Jyotir(Light) linga(Source): August 2015

When a lighted matchstick is shown before a source of light, the matchstick, being opaque obstructs the light from the source and acts a shadow of it on a screen.

The flame of the matchstick itself is a source of light. The flame throws its own light to fall on the region beyond it and cannot prevent the light from the other source too. Hence the shadow of the flame is not formed