To help us discover our various sorts of illusion and to rectify them by reasoning so as to enable us to proceed progressively towards the Path of enlightenment may be said to be the professional work of Buddhism. For this reason, Buddhism is said to be absolutely rational: not only it is unmixed with, but also free of, every sentiment, and in this respect, is completely identical with Science. Though Philosophy is also established on rational basis, it cannot be gainsaid that among those different schools of Philosophy, as far as their theories are concerned, there is no lack of biased views, dogmatism and subjectivity. This also holds true with other subjects of Social Science. Literature and Arts, where sentiment plays the predominating role, and where sentiment is strong, reasoning is weak, this is why, since thousands of years ago the work to make correct evaluation of Literature and Arts has been rather difficult. Feeling and reason usually and mutually counteract each other; when emotion gets the upper hand, reason flies out of the head, and when reason prevails, such feelings as fear, craving and so forth all give way. Parental love is a natural feeling but if it is carried to excess, one would not be able to understand the youngsters and their conduct correctly. Again, if patriotism bursts out for no cause, it would become chauvinistic, fanatic and calamitous. If male and female, desperately in love with each other, are unable to overcome obstructions standing in the way, they would lose their head and do such foolish thing as to commit suicide. In the eyes of Buddhism, all these private and public feelings, because they are overdone, are foolish and blind love, therefore on no account should we allow emotions to get the better of us. Thus, the Surangama Sutra says: The reason why sentient beings may ascend or descend at the six levels of Transmigration is this: if emotion prevails, they would to go heaven; if there is emotion without conception, they would go down to hell; if there is half emotion and half conception, they would be born as human beings."
The critical attitude of the scientists is absolutely unsentimental, impersonal and with strong accent on the power of imagination. In view of the inadequate visual power of human eyes, we have to depend on our imagination to help us visualize the structure of atoms, the movement of the Celestial Body, transmission of electric waves, and the complicated structures of various scientific instruments. Projective Geometry, for example, is a subject where most far-fetched imagination is required.
In Buddhism a good many Dharmas under the general heading of Chan Meditation take to imagination as a means of cultivation. The Five Meditations are a case in point: 1. Meditation on impurity of the body, 2. Meditation on Breathing, 3. Meditation on Compassion, 4. Meditation on Causality, and 5. Meditation on either the six levels of Transmigration of the eighteen Spheres. Besides, there are Meditative Insight into the Unreality of all things, Complete and Immediate Meditation, Meditation on Mere-Consciousness, Meditation on the Ten Realms, and as pointed by Meditation on Amitabha Sutra, the Sixteen Meditations. According to the last-named Meditations, some of them are concerned with the principles of Buddhism and some with material phenomena. In the Meditation on impurity, the object of meditation is the structure of the human body, and in the Nine Meditations, the process of decomposition of the dead body is meditated upon. Of the Sixteen Meditation, the First One is meditation on the setting of the sun at the western Paradise, and if the image can be clearly perceived whether with eyes opened or closed, the meditation would be considered well done. In the subsequent meditations from the Second to the Last ones, the objects of meditations are the people and things of the Supreme Happiness Buddhaland. To practise those Meditations calls for a high degree of imagination and so corresponds with the principle of Projective Geometry. Because he had had training in the study of Projective Geometry at school, the writer had experienced little or no difficulty in practising the First Meditation on the setting sun. This was corroborated by a distinguished Chinese Mathematician, the late Dr. Wong Chi-Tung, who used to practise the First and the Second Meditations with the most gratifying results. At all events, whatever meditation one may practise, intensive training of concentration and imagination is of fundamental importance on no account should such feeling as craving, fear, despair, disgust, etc. be allowed to enter into the meditators mind, otherwise one would run the risk of going the Devils way.