The Thumb meditation is one of the most simple yet very intense ways to direct the mind to become aware of an object-your thumb. In Yogic terminology, this is called Trataka. However, in Yogic systems, an oil lamp is used to gaze up. Here, you only are aware.
The difference is that in Thumb Meditation, you become one with the object and the ego-self vanishes, leaving only awareness to exist.
When one can practice the thumb meditation for over 29 minutes, one will become One with awareness. The ego-self vanishes.
Below is the link to the audio of the Thumb Meditation.