Mahadev - beautiful Shiva, a perfect form to meditate on..alternatively one can meditate one one's favourite deity (Isht Dev) such as Rama/ Krishna/ Divine Mother Durga-Parvati (the consort of Lord Shiva).
“He is the source of light in all luminous objects. He is beyond the darkness of matter and is unmanifested. He is knowledge, He is the object of knowledge, and He is the goal of knowledge. He is situated in everyone's heart.”