Every philosophy is sustained by a number of elemental principles that give it cohesion and unity. Ockham's is no exception. The principles of the divine omnipotence and the rule of parsimony of thought known as 'Ockham's razor', and others like the principle of non-contradiction, help to shape the entire range of his thought. Many of his conclusions on matters as diverse as God's knowledge, will and power, on creation and the causality of natural things, and on human intuition and morality are reducible to them. These principles are not unique to Ockham but were common to all the scholastics. Yet it is precisely in confrontation with the views of his predecessors and contemporaries such as Scotus, Henry of Gent, Aquinas and Chatton that the particular force and character of his thought are revealed. Over and again he sets each principle to powerful use, but allows no single one ot dominate, or to yield all its consequences. Martin Heidegger once declared, 'Every thinker thinks but one single thought'. The original and focal point of Ockham's thought is the singular or individual thing (res singularis), as common nature (natura communis) is the central conception of Scotism, and the act of existing (esse) is of Thomism. With Ockham the traditional conjugations of being come to signify the thing itself in its ineluctable unity. The concept of being is univocal, standing for and signifying individuals. A being is radically diverse and incommunicable, differing from every other being not only in number but in essence. Indeed, an individual thing can no longer be said to have an essence; it is an essence. Ockham takes his place among the great philosophers because, like them, he drew out all the implications of his insight. He remains a seminal thinker: his denial of common essences, his emphasis on language in philosophical discourse, all anticipate significant developments in modern philosophy.