p Knowledge always begins with a study of objects of the outside world with the aid of our sense organs. This we know from our day-to-day experience. If we want to study an unfamiliar object, we first of all carefully examine it, and, if need be, touch it with our fingers, taste it, etc. Direct perception of things is the initial phase, the first step on the road to knowledge. Man, on coming into contact with objects and phenomena of nature in the course of his practical activity gains his first impressions of these objects and phenomena through his sense organs. The sense organs are a kind of a window through which the outside world “penetrates" man’s consciousness and which enables him to perceive the colours, odours, and sounds of nature, the taste of its fruits, etc.

p Sensation is the main form of sensory knowledge. Sensation is a reflection of individual properties, distinctions or sides of an object. Objects can be hot or cold, dark or light, smooth or rough—all these and many other properties, acting on our sense organs, arouse certain sensations.

p Man’s organism possesses a corresponding physiological apparatus for the formation of sensations. This apparatus consists, firstly, of sense organs, secondly, of nerve fibres through which, just like electricity along wires, excitation is transmitted to the respective parts of the cerebrum and, thirdly, of the sections of the brain where the excitations are transformed into corresponding sensations. Excitation caused by a definite sound in man’s ear is transformed into the sensation of sound, while the action of light on the eye is transformed into the sensation of light, and so on.

p What makes sensations tremendously important in the process of cognition is that they provide material enabling us to judge an object The entire subsequent process of knowledge rests on the information about objects which sensations give us.

p Lenin defined sensation as a subjective image of the 157 objective world. This means that sensation, being a reflection of objectively existing objects, is not their mechanical imprint on man’s brain, but an ideal image. This image is subjective because it belongs to man (subject) and to humanity, and not to the outside world. This means that the nature of sensation is influenced in a certain way by the specific features of the psyche, the individual qualities of the given person, and above all by social conditions, by his social environment.

p One of the main indications of the subjective nature of sensations is the fact that people differently perceive identical outside influences.

p Does this mean then that sense organs give us an incorrect idea of the world? No, it does not. Daily experience and scientific data prove that sense organs do not deceive us. If the indications of one sense organ arouse doubts, we turn to the others. If a man does not believe his own eyes,he resorts to the use of his fingers, and if this is not enough, he has at his service the eyes and fingers of other people. If, lastly, even this is not enough, man turns to instruments, experiments, practical experience. Thus, sense organs, checked by each other, by the sensations of other people, by experience, experiment and practice, give us, on the whole, a correct idea of things accessible to us.

In addition to sensations, sensory knowledge consists of perceptions and ideas. Perception is a higher form of sensory knowledge. It reflects an object in its sensory, direct entirety, the total of its external aspects and distinctive features. An idea is the reproduction in man’s mind of earlier perceptions. We, for example, can reproduce in our mind, can bring to mind the image of our teacher, although we may not have seen him for many years.