Isa, Prasna, Katha, Tapaniya and other Upanishads elaborately treat the method of contemplation of Brahman, as devoid of qualities. Badarayana, in a chapter of Brahma-Sutras which deals with the nature of qualities of Brahman, mentions positive attributes like 'joyful,' 'intelligent,' etc., as well as negative attributes like 'measureless,' 'colourless,' etc. Both kinds of attributes are referred to the absolute and yet the contemplation of such a Brahman can be called Nirguna-Upasana or meditation on conditionless Brahman. The chief distinction between the contemplation of the conditioned (Saguna) and unconditioned (Nirguna) Brahman is that in the former the devotee looks upon it as really connected with those attributes, while in the latter, positive and negative qualities are not viewed as essentially connected with it, but as suggesting its absolute nature. Hence, joyful etc., do not enter into the essence of the contemplated Brahman but act as a gateway for grasping its true nature. In the contemplation of the conditioned Brahman, those and similar other properties form a part of the contemplation.
The term Nirguna does not mean that Brahman is a negative concept, the Brahman is a non-entity or zero. It means that the qualities found here in limitation, are found illimitable in Brahman. It means that the attributes are Brahman's essential nature or His Svarupa. It means that Brahman does not possess perishable qualities of matter like the blue colour of a cloth but possesses all auspicious qualities (Sarva-Kalyana-Gunas). Brahman is Nirguna-Guni. So also, by Nirakara, it does not mean that Brahman is formless. It means 'He has not got a limited form as that of objects, but has a form unimaginable.' What form can you attribute to infinity? Many have a crude idea of Brahman. They say "Brahman is a block of stone because He has no qualities. He is a regular void, a zero." No. No. They are entirely mistaken. They have not made Sadvichara. They have various doubts. They have a gross intellect which is unfit for philosophical investigation (Vichara), discrimination, reflection, ratiocination, etc. They have not studied the infallible Upanishads, the right means of knowledge, the right source of wisdom which gives an accurate knowledge of Brahman. Upanishads are infallible, because they appeal to the reason of every thinker, every philosopher. They tally with the experiences of realisation. Hence they are infallible. Their authority is more valid than that of perception or inference. Brahman is extremely subtle. He is finer than a thousandth part of a point of a hair divided into a thousand parts. A subtle, calm, pure, sharp-pointed, clear and one-pointed Suddha Buddhi is needed for understanding and meditating on Brahman. They suffer from Samasya-Bhavana, doubts regarding the validity of the Upanishads, and the true nature of Brahman. They should purify the mind by selfless service, should study the Upanishads, should develop the four means of qualifications, should have constant Satsanga. Then, they will have intellectual conviction and intellectual grasp of Brahman. By Sravana, by Manana and by Nididhyasana they reach Brahman. This is the royal road. So, Brahman is full of auspicious Gunas. He is a lump of luminosity. He is Prajnana-Ghana. He is a solid mass of knowledge. He is really more solid than the Himalayas. Knowledge is more heavy and more concrete than a huge block of stone.
In Saguna meditation, the devotee considers himself as entirely different from the object of worship. The worshipper makes a total, unreserved, ungrudging, self-surrender to the Lord. He respects, honours, adores the Lord and depends on Him for everything, for food, protection and his very existence. He looks always for help of any sort from the Ishta Devata. There is nothing independent for him. He is an instrument in the hands of the Lord. His hands, legs, senses, mind, Buddhi, physical body belong to the Lord. A devotee does not at all like the idea of Jnana or merging. He likes to have his separate entity as a servant and to serve, worship and love the Lord always. He does not like to become sugar as a Jnani, but like to taste sugar and eat sugar. This method of worship is one of contraction. Suppose there is a circle. You have a position in the centre. You contract yourself to a point and merge in the circumference. This is Saguna meditation. This is suitable for people of emotional temperament. Vast majority of persons are fit for this line of worship only.
In Nirguna meditation, the aspirant takes himself as Brahman. He denies and sublates the false adjuncts or fictitious environments as egoism, mind and body. He depends upon himself and upon himself alone. The aspirant asserts boldly. He reflects, reasons out, investigates, discriminates and meditates on the Self. He does not want to taste sugar but wants to become a solid mass of sugar itself. He wants merging. He likes to be identical with Brahman. This method is one of expansion of lower self. Suppose there is a circle. You have a position in the centre. You so expand by Sadhana to a very great extent that you occupy the whole circle, and envelop the circumference. This method of meditation is suitable for persons of fine intellect, bold understanding, strong and accurate reasoning and powerful will. Only a microscopic minority of persons is fit for this line of meditation.
It is comparatively easy to meditate on 'Aham Brahma Asmi' when you are seated in a steady posture in a solitary closed room. But it is very, very difficult to keep up this idea amidst crowded surroundings, while the body moves. If you meditate for one hour and feel that you are Brahman, and if you feel for the remaining twenty-three hours that you are the body, the Sadhana cannot produce the desired result. So, at all times, you must try to keep up the idea that you are Brahman. This is very, very important.
A worldly mind needs thorough overhauling and a complete psychological transformation. Concentration and meditation bring about the construction of a new mind, with a new mode of thinking. Contemplative life is diametrically opposite to worldly life. It is an entire change altogether. Old Vishaya- Samskaras have to be thoroughly annihilated through constant and intense practices carried on with zeal for a long time and thereby new spiritual Samskaras have to be created.