The fourth step of Preksha meditation is perception of bright white colour on the Centre of Enlightenment.

Concentrate your mind on the Centre of Enlightenment, situated in the middle of your forehead.
Allow your mind to penetrate inside and perceive bright white colour there. You may visualise as if the bright white light of the full moon is spreading throughout the portion or visualise the bright white colour of the snow or any other white thing. Practice concentrated visualisation of bright white colour on the centre of enlightenment.

Perceiving the bright white colour, experience through auto-suggestion that all your passions & emotions are being pacified. All your excitations are subsiding. Your anger is waning away.
Now allow your mind to spread throughout the whole portion of your forehead and perceive the
bright white colour there. Visualise that the particles of bright white light are permeating the whole portion of the forehead, covering the emotional area in the frontal lobe of your brain.

Continuously perceive bright white colour and experience complete tranquillity,
complete mental peace and bliss.

Conclude the meditation session with two or three long breaths. 

 Appana Sachchamesejja, mettim bhuesu kappae.

Search truth yourself and befriend all living beings.

For emancipation from sufferings, practice knowledge and conduct.

�3 times

I seek refuge in the adorable ones.

I seek refuge in the emancipated ones.

I seek refuge in the saints.

I seek refuge in the religion propounded by the omniscient ones.

Now adopt the posture of obeisance, that is kneel and bow, pay obeisance to truth.
With folded hands first inhale fully and then during exhalation, pronounce the Aphorism of Faith ---

"Vande Sachcham" �3 times

"I pay my obeisance to Truth"

by bowing down to ground. Repeat it three times. Meditation session concludes.