You will see how, if you will again stand in front of the mirror and stretch out one arm toward it. The simplest test is made, if you can arrange that the light shall be directly at your back, for then it is reflected by the mirror on to the front of you. In this case you will notice that your outstretched hand receives the most light, because it is nearest to the light. If it were represented in this way in a picture, our habit of seeing the highest or brightest light on the highest or most directly exposed surface of an object would make us feel that the hand projected in front of the body.