Philosophical investigation can be compared, in a way, to medical diagnosis and investigation. It is a subtle and in-depth understanding of the basic components of experience, similar to the investigation of various methods of medical application, as in the case of a chronic illness. Inasmuch as the organism of the body is internally related, the parts are connected to one another in an inseparable manner. Hence, when a part is investigated into, its relevance to the other parts cannot be ignored. Medical examination is a difficult subject. When a particular part of the body or an organ is ill, a good physician may have to understand the causative factors embedded in the whole system, and not merely in that particular organ. When a person is ill, even if it is by a mere cold, the whole body is ill, not merely the nostrils, or the nose. The illness is expressed or manifested through a particular channel, but the disturbance is in the entire organism. Likewise is human experience. Human problems do not come merely from one side, just as one is not ill only in one part of the body, though it may appear that he has only a sore in the foot, or a cold in the nose, or an ache in the head.

Thus, one may attribute the cause of his difficulties to certain factors of life. As mentioned earlier, man, mostly, attributes the causes of his experiences to social factors. This is an inadequate understanding of the situation. The outermost and the immediate phenomenon that man generally confronts in his life is society, though the world is not made up merely of society. Nevertheless, he seems to be concerned only with that on account of a feeling that he is primarily involved in human affairs, and other things in the world are secondary, a notion that enters into his mind for obvious reasons. We are human beings, and, so, it is natural for our mind to assess things in a human manner. Cows go with cows; buffaloes go with buffaloes; frogs go with frogs; men go with men. They cannot go with anything else. This is a biological instinct that is at the root of man's reactions. Thus, man's philosophy becomes a human philosophy, and his efforts seem to be directed to human ends, and there is nothing else that can occur to his mind. But, to bring the analysis of medical examination once again, a mere human approach is not a proper scientific approach. The physician does not approach a patient as a father or a friend, but as a scientific impersonality who wishes to understand and not merely emotionally react. Oftentimes people's experiences are emotionally stimulated. They are stirred up in some measure in their emotions when they wake up in the morning and meet their friends. Their confrontation with their friends and their enemies is emotional rather than intellectual, rational, or philosophical. People are suddenly roused up into a feeling of satisfaction, or are plunged into a mood of melancholy or depression, which even though stimulated by non-human factors, seems to pass over from human beings. Though natural and important causes may be behind man's difficulties, like a wind that blows, or a flood that occurs in a river, or an earthquake that shakes him, man interprets them and tries to understand their relationship to him in terms of human beings.

A philosopher is not expected merely to think as a man or a human individual. The beginning of philosophy is the struggle of the mind to rise above the mere human perspectives. A difficult thing it is to become a philosopher! It is not merely reading a book, or going through the range of the history of the thoughts of philosophers. One can become a professor of philosophy, but not easily a philosopher. A philosopher is one who has an insight into the substantiality of things, and not the appearances they put on in their mutual relationship.

A philosopher must be able to stretch his mind beyond what merely appears to the eyes, into the field of what is not substantial and tangible, even if it may be of notions or concepts. Most of the matters that are important to man are mere concepts. Without these concepts and notions, he cannot live. They are necessary notions. For example, human society is a phenomenon that can be cited. Really, there is no such thing as society. It does not exist. What is there is only a heap of individuals. There are men and women and children. Nothing else is seen. Society cannot be touched. It cannot be even seen with the eyes. A society is a psychological interpretation of relational circumstance, so that it becomes a relation and not a substance. So are administrations, governments, etc. They are not visible to the eyes. Only people can be seen. The building bricks of administrative organisations, even of the human society for that matter, are the individuals which are the substances. So, when an attempt is made to define the content of philosophy, one would be landed in the definition of a substance, an existent something, rather than a notion. A distinction has to be made between a substance and a notion. An obvious example of this difference, as seen above, is the human society, which should be regarded as a notion, though a necessary notion. Every organisation, every institution is a notion. It is an idea which has been projected by a group of people for practical convenience in day-to-day existence. But, substantially, only people exist and not relations. What are relations then? The relations are psychological.

When a body, an organisation, or an institution, is to be formed, or a system of action is to be set up, minds join together, and act and react in a particular manner. This psychological action and reaction in a requisite manner is the organisation, and, if this action and reaction ceases psychologically, there is, once again, a discrete, isolated phenomenon of individuals existing without any society. If there were no mental reactions in human beings, they would remain as mere substances, isolated individuals, and not form a society or anything of the sort. So, in a philosophical study, the basic substance is investigated into so that it becomes easy to know what reactions it sets up through the characteristics it possesses. Human substances, called individuals, set up human reactions, and, therefore, there are human institutions - whatever be the largeness of these institutions. From two persons becoming friends and enlarging this friendship into a family group, it can expand into a community of people and, further, into a national spirit or an international organisation, and so on. Yet, the principle is the same. Human minds act and react. Therefore, what is called a social set up, whatever be the extent or the dimension of it, is psychological and not physical.

No human institution survives for eternity. All empires came and fell. No kingdom succeeded for eternity, and no institution can, because all institutions which are humanly organised are conditioned by the evolutionary factors to which the minds of people are subject, and, as there is an advance in evolution, there is, naturally, a change in the set up of psychic actions and reactions. Therefore, human institutions cannot be perpetually established in the world. No family, no nation, no empire can stand for ever, because it is not permitted by the law of evolution, just as one cannot be a baby always, though one was a baby once upon a time. A baby becomes a mature person, and advances. The systems of organisation in the form of social institutions grow into maturity, and they become old like the individual; then they decay, and they perish. The law of growth and decay that is seen in the individual personality and things operates even in institutions. This is so, because institutions are only manufactured goods psychologically projected by the characteristics of the individual, which are subject to this evolutionary process of growth, decay, and final extinction. The whole world seems to be subjected to this law of evolution. Nothing can stand in the same condition for ever.

Now, when one observes this phenomenon of change to which everything seems to be subject, including human individuals, one is dragged, perforce, into a need to investigate into that which changes. If there is change, something is changing. It is not that change itself is changing. Change is a process. It is a condition into which something is subjected, through which something passes. What is this something which is evolving, which changes, which is subject to transformation, which grows, decays, and, finally, becomes transformed into extinction? This is the way in which a philosophical mind works. It cannot be satisfied with a mere first vision of things. A credulous mind or a baby's intellect takes things for granted. A toy is a toy, and it cannot be anything else. It is something worthwhile for a baby. But to a mature mind, it is a useless tinsel, which has no value. The value of a thing changes on account of a new interpretation to which it is subject. So, while man's thinking is generally like that of children - even for grown-ups a building is a building, a land is a land, a man and a woman are a man and a woman, everything is as it is seen by the eyes to the prosaic perception - a philosophical analysis is a capacity specially exercised by the mind to delve deep into the substantiality of things rather than the contour which experiences put on. Things are not what they seem to be, and nothing is what it appears to be. History, whether it is astronomical or social, is a proof of the impossibility to finally trust anything as it is made visible to the eyes.

Philosophy is a study of causes behind events, or, rather, the causes of effects, or, to push it further, it may be said to be a study of the ultimate cause of things. This is the subject of philosophy. Why should there be anything at all, and why should it behave the way in which it behaves? It is often said that science is distinguished from philosophy in this that, while science can tell the 'how' of things, it cannot explain the 'why' of things. That is not its field. The 'why' of anything is investigated into by the study known as philosophy. Unless the question as to the 'why' of a thing is answered from within oneself, one cannot feel finally contented. There is a mystery hanging above our heads, and everything seems to be a mist before us. Why should anything conduct itself or behave in the way it does? Social philosophies of different types study the nature of human behaviour. The science of sociology, again, confines itself to the 'how' rather than the 'why' of human behaviour. "How do people conduct themselves, and how do they behave in human society?" it asks. But we have a different faculty within us which puts the question: "Why do these people behave in this manner?" We often say, "I do not know why people are behaving in that way." Philosophy studies everything that it sees, everything that it senses, and anything that it can think of in the mind. It puts the questions of 'how' and 'why' to everything, and anything; - to every blessed thing. Any object of experience is subjected to analysis of this kind to the very core, threadbare, and one tries to go deep into its very roots. Every experience, external or internal, is an object, or a subject, of study in philosophy. Philosophy is a comprehensive science, if at all we can call it a science. It is a science in the sense that it is a systematic study, a logical approach, and does not take things for granted. It proceeds from the visible to the invisible. We may say, it proceeds from the particular to the general. This is the inductive system in philosophical analysis. Or, sometimes they say, the method adopted is called the Socratic method - a questioning attitude, a question which questions the question itself, and does not take anything for granted until a satisfactory rational ground is discovered behind the causes of these questions, which constitute human life in its present form.

Thus a philosophical insight is an awakening of a new light from within, with whose aid one can illumine the dark corners of the earth, and endeavour to see things in their true colours, rather than be carried away by their chamaeleon-like shapes and presentations.

Philosophy is the vision of facts as they are, divested of the imagination by which circumstances in life are construed to be quite different from what they really are.

The history of philosophy gives a list of great thinkers who conducted such investigations. It is also necessary for us to cover the range of all the possible channels of approach to the essence of things, which philosophers call Reality.