The alchemists went a step further in their classification of things. They asserted that there is One Thing present in all things; that everything is a vehicle for the more or less perfect exhibition of the properties of the One Thing; that there is a Primal Element common to all substances. The final aim of alchemy was to obtain the One Thing, the Primal Element, the Soul of all Things, so purified, not only from all specific substances, but also from all admixture of the four Elements and the three Principles, as to make possible the accomplishment of any transmutation by the use of it. If a person ignorant of its powers were to obtain the Essence, he might work vast havoc and cause enormous confusion; it was necessary, therefore, to know the conditions under which the potencies of the Essence became active. Hence there was need of prolonged study of the mutual actions of the most seemingly diverse substances, and of minute and patient examination of the conditions under which nature performs her marvellous transmutations. The quest of the One Thing was fraught with peril, and was to be attempted only by those who had served a long and laborious apprenticeship. In _The Chemical Treatise of Thomas Norton, the Englishman, called Believe-me, or the Ordinal of Alchemy_ (15th century), the adept is warned not to disclose his secrets to ordinary people. "You should carefully test and examine the life, character, and mental aptitudes of any person who would be initiated in this Art, and then you should bind him, by a sacred oath, not to let our Magistery be commonly or vulgarly known. Only when he begins to grow old and feeble, he may reveal it to one person, but not to more, and that one man must be virtuous.... If any wicked man should learn to practise the Art, the event would be fraught with great danger to Christendom. For such a man would overstep all bounds of moderation, and would remove from their hereditary thrones those legitimate princes who rule over the peoples of Christendom." The results of the experimental examination of the compositions and properties of substances, made since the time of the alchemists, have led to the modern conception of the chemical element, and the isolation of about seventy or eighty different elements. No substance now called an element has been produced in the laboratory by uniting two, or more, distinct substances, nor has any been separated into two, or more, unlike portions. The only decided change which a chemical element has been caused to undergo is the combination of it with some other element or elements, or with a compound or compounds.