Spiritual knowledge is a regular science. Just as two and two make four, similarly everything is clean and obvious here also and there is no scope for any kind of modification or change in that.
Excerpt of the talk "Man! Know thyself" given by Sant Kirpal Singh
Since the beginning of creation, when the first flicker of self-awakening dawned on man, his attention has been more and more concerned with the problem of his own worldly existence and the investigation into the cause and source of all creation. For ages, he has probed and queried in vain, but now, at last, his increasing thirst for knowledge is turning him to study the results achieved by others in the field.
Ancient and modern sages asked, "What is that, the knowledge of which makes everything else known?" and in the same breath replied, "Knowledge of the higher self – the true man." So the supreme knowledge is that which deals, both in theory and practice, with man's true nature and his relation to God. It is, in fact, a natural science without a hypothesis, subject neither to change nor time. In ancient India it was called 'Para-Vidya' (science of realized truth or science of the beyond) and different denominations sprang up to interpret this knowledge. The term 'Apra-Vidya', standing for preparation for achieving the knowledge of 'Para-Vidya', was then introduced. This preparation consists of following an ethical and moral life, and the practice of concentration or meditation (in so many ways) both being indispensable for spiritual development.
Man is constantly changing or introducing new names and terminologies to describe this science. The Masters were called Sants, and the nature of knowledge Mat, thus giving us the term 'Sant-Mat', which is at present mostly used to name the path of the Masters. Other terms, such as Shabd Yoga, Surat Shabd Yoga, Sehaj Yoga, are also used to describe the same science. In the Sanskrit language, the word 'Sant' means Master of the highest order, and 'Mat' is a confirmed opinion or statement made by an adept after personal experience. The foundation of this science, therefore, is the result of a critical study, minute investigation, and the lifelong personal verification of facts based on practical experience of the self in man. This experience of the self is something that a competent Master is prepared to give to each individual who approaches him. Sant Mat, therefore, is the teaching, system and path of the Saints.
The Masters do not attach any importance to names, designations, or the fact that many religious sects, groups and circles, have claimed this science as their own and named it after their leaders or founders. They look upon these groups as schools where man – the noblest being in creation – can study with other men as children of one and the same almighty father. A Master (also called Sant Satguru), has complete mastery of both the theory and practice, and is competent to impart both knowledge and experience to all sincere seekers after truth, without any distinction whatsoever of colour, caste or creed. Any man or woman, whether rich or poor, young or old, sage or sinner, learned or unlearned, who is able to grasp the theory of the Science, has a right to acquire this knowledge.