From Direct Experience of Reality: Verses 8 to 12
Devoted trust (bhakti) in the words of the holy scriptures and the teacher is called faith (shraddha); one pointedness of the mind on the one real goal of life is called concentration (samadhana). 
Commentary: The scriptures are above logic, though their truth can be established by right reasoning. Unless a pupil has faith in the passages of the scriptures which contain the direct spiritual experiences of the sages, he will remain imprisoned in the web of doubt. Reason cannot solve the doubts a man may have about the authority of experience. Man cannot live without faith in some kind of authority. In Western philosophy reason is assigned the supreme position. Our holy Acharyas believe in reason (tarka), but they are not slaves to it. The philosophy which is based on reason alone is as changeable as a weather-cock in the wind. Aristotle held his domain for over a thousand years; but he was overthrown by the appearance of new systems of reasoning and experiment. When Hegel offered his philosophy in the last century, many accepted it as the last word. Nowadays Bertrand Russell calls Hegelianism a tissue of errors from A to Z.
Reason functions in the realm of duality. Its functions are analytic and synthetic, but it is powerless in the realm of non-duality. Students of history, geography and physics take for granted the statements of the authors of their text-books. William James, Bergson and many other brilliant intellects of our time do not think the intellect competent to judge the highest truth.
Thus in matters spiritual the Shruti claims full authority. The ancient texts are explained by a competent teacher. To defend the statements of the Shruti, Shri Shankara Acharya, who is held to be the greatest dialectician in the world, uses reasoning of a most subtle kind. We do not discount the use of reasoning but accord it its rightful place. In fact, great emphasis is laid by Shri Shankara on the value of vichara (ratiocination) in the philosophy of Advaita, an exact system of thought in which logic plays a most important part. Many classics have been written to establish the truth of the Shruti by reasoning, such as Advaita Siddhi of Shri Madhusudana Sarasvati and the great works of Shri Harsha Misra and Vachaspati Misra. Another important item of discipline is to focus the mind wholly on the goal of life, the spiritual awakening of man.
“O all pervasive Lord, when and how shall I be freed from the bondage of this ever-changing world?” This aspiration firmly fixed in the intellect is called the desire
for release (mumukshuta). 
Some are pessimists, some are optimists, while some call themselves realists and try to transform the world into a source of perennial joy and freedom. Indeed it is commonly held that this is possible. In mid-Victorian times scientific advance and constitutional reform on democratic lines were held to be sure means to real progress in peace, prosperity and freedom. But so far the world has not become any less dangerous for man. Science is being exploited to destroy mankind for political ends; the ideal of democracy is merely a tool in the hands of self seeking politicians. Is man doomed to suffering and bondage for ever? Must we accept the conclusions of the materialists and believe in the non-existence of Providence?
There is another school of thought which holds that above the clouds of ignorance the sun of happiness and liberty shines in full splendour. The world does not affect the whole of human personality; the essence of man’s existence is truth. The reforms of the realm of ignorance have a certain meaning, but they do not touch truth absolute. The limitations under which man works imply the existence of a state of consciousness beyond all limitations. The spirit being infinite and absolute is imprisoned phenomenally in the realm of nescience. The sages have gone beyond it and do so even today. Has this philosophy any social application? Is it escapism, as Albert Schweitzer holds? No, not at all. The good Schweitzer’s approach is unphilosophical as he has hermetically sealed his intellect against any expression of truth other than narrow Christianity. The application of the philosophy of Advaita to our daily life begins with the idea of the brotherhood of man and the fatherhood of God. The world is a school in which we learn how to practise virtue and live with all in peace and brotherly love. There is no instance in the history of the world of a statesman, conqueror or humanist who can say what the adherents of Advaita have emphatically declared: “I have found all that was to be found; I have known all that was to be known; I am at one with the highest good”. This state of truth is open to anyone who cares to study and discipline himself with a view to its attainment. The holy Acharya here gives expression to this state of the mind. It consists in the desire to end the darkness of limitations and to enjoy for ever the light of the spirit. This aspiration must occupy the first place in our heart.
The man who is endowed with the disciplinary qualities mentioned above and is devoted to the highest good ought to exercise his faculty of reflection and ratiocination to achieve the knowledge of truth. 
The highest good is the vision of truth eternal and imperishable in a man’s own Self. A candidate for this exalted state of Self illumination must equip himself with the qualifications mentioned in the above verses, and then exercise his faculty of thought to separate the chaff of unreality and illusion from the grain of truth. The vision is not obtained through any other means but calm and deep reflection. Here lies the importance of the exercise of logic and reasoning.
Many candidates to the divine vision within want to obtain peace and illumination but neglect the great discipline laid down in these verses. They will not obtain the divine consciousness. Some people begin to find fault with Yoga’s promise of liberation. Many immature souls take to the study of Vedanta under the impression that they can acquire spiritual perfection and at the same time enjoy the pleasures of the sense objects. They will miserably fail. Renunciation is the keynote of the divine music. Mere logic-chopping or the blind reflections of men who believe in nonsensical systems lead nowhere in the divine realm.
As in the absence of physical light the objects are not revealed, so the realization of the Self (jnana) is not obtained without cogitation (vichara). 
An objection sometimes raised by those who have only a nodding acquaintance with Vedanta is that it is based on dogmatism and cannot therefore be called a rational system. In this verse supreme importance is assigned to reflection by rational means on the Vedantic truth postulated by the holy Shruti. A man may be charitable and do good to others and even practise external devotion in the form of rituals, but for direct realization he must perform ratiocination. Self analysis is a very important element in the cognition of the reality within. The method of self analysis is like the method used by Euclid in geometry. Faith plays an important part even in logic. Unless a student has faith in the competence of logic to reveal truth, he cannot undertake a rational enquiry into it; he does not try to prove the competence of proof. Logical rules are taken for granted. Mind cannot reveal the truth but it can help to establish it by logic and proper reasoning. Logic can also be abused, as it is by the supporters of dialectical materialism. This is an important point and merits careful examination. Those who want to make a further study of this aspect of Vedanta are referred to the works of Shri Harsha Misra, Shri Vachaspati Misra and the great Madhusudana Sarasvati.
“What am I? How is the world created? Who is its creator? What is its material cause?” This is the reasoning called cogitation (vichara). 
Sometimes unproductive logic-chopping is described as vichara. In the contests of logic known as Nyaya Shastra, in which I used to participate in my student days in Benares, hours would be spent in controversy on subjects far removed from any practical bearing, and yet this was called vichara. This verse gives a typical example of true vichara (cogitation). The chief function of a knower is others in to know himself. Am I matter or mind, or something other than these two? What is this world spread out before me in time and space? How has it been caused? Is it a machine created by itself? Or is it the work of a Creator? If so, what is His nature? What is the stuff of which the world is created? These are most important questions because on the answer to them depends the choice of the ideal to be pursued in life. This is an enquiry into the enquirer. It should be conducted independently and on logical lines. It is an excellent practice in the application of thought. We can deduce our right conduct in society from our answers to these questions. Now follow a few conclusions from this sort of cogitation which a student has to verify for himself by his own reasoning.
“I am not the body, which is a combination of material elements, nor am I a collection of the senses. I am something different from both these.” This is the reasoning called cogitation (vichara). 
Here is a further illustration of vichara, which does not mean unbridled reasoning. If one gives full rein to the mind, the result is sure to be chaos. Cogitation has to be performed within certain well-defined limits. It is an attempt to focus the mind on the outer fringe of the Self, where it can receive more of the spiritual light and be rendered fit for absorption in the spirit. This kind of cogitation can be said to be dynamic meditation and is a method whereby the mind does the negative work necessary to prepare itself for deeper meditation on the Self. Shri Bhagavadpada Acharya shows how to make the best use of the logical faculty. When a man is convinced that he is fundamentally spirit and not body and mind, great ethical ends are served; detachment becomes easy and natural, and the mind can no longer be imprisoned in the love of names and forms and appearances.
“I am not a collection of senses”. How can this be known? Because I am the subject, the witness of the mind and the senses. The subject is entirely different from the object. It is clear that the perceiver is not the perceived. In the final analysis of the personality it is found that even the empirical perceiver is in the realm of avidya (nescience), the not-Self. When Aristotle in the concluding part of his Metaphysics speaks of a life devoted to the contemplation of the Reality in perfect detachment as the ideal life, he means the sort of cogitation which is described here by the holy Acharya. A new world is revealed to the Yogi by the practice of this method. His mind is absorbed in a serenity in which all other joys are infinitely surpassed.
“The whole world is a product of nescience; it disappears on the dawn of true knowledge. Its real creator is the mental activity (sankalpa) of many kinds.” This is the reasoning called cogitation (vichara). 
In this verse the holy Acharya lays down a prominent principle of the philosophy of Vedanta. Two questions were asked in the previous verse: “What is this world?” and “Who is its creator?” The world is a creation of nescience in the form of the various activities of the mind. What is this nescience? It is a principle which is positive and beginningless, but which can cease to exist. As the mind itself, which thinks and wills and feels, is a modification of this nescience, it cannot know it. Here the creation is said to be a product of the mind. This is the cornerstone of the philosophy. Nescience is neither real nor unreal. If it were real it would continue for ever and there could then be no possibility of release from its bonds or limitations. In that case all practice of righteousness, devotion and learning would be useless. If this position is accepted as true, then how can we account for the desire of the soul of man to be free from all limitations? Everyone wants to be happy and longs for a state of happiness which has no end. When this desire is enveloped by ignorance, we imagine that youth, health, wealth reputation and sex-love can give happiness. Is there no end to this process of becoming? Yes, there is. When the spirit is freed from its relationship with the mind in the state called enlightenment (jnana), the world as a conglomeration of conditions disappears like the mirage river in the desert. The world exists in the mind and is a product of the mind. Here the word ‘mind’ covers both its aspects, macrocosmic and microcosmic; the human mind imposes its sub-creation on the projection of the cosmic mind. Real vichara means cogitation on this line of thought. Endless dialectics are permitted in the course of this vichara. We study both Eastern and Western philosophy, by way of comparison.