It is the object of this chapter to give some account of the speculations on nature and spirit which occupied Bruno during his first year in England, and which show how hard he was striving to pierce through the shell of mediæval thought in which his mind was encased. However fiercely he struggled to gain his freedom, it was impossible that he should do so quite at once. With all his contemporaries, he was imbued in Aristotle's ways of thought, and the problems he set himself to answer were largely determined for him by Aristotle. The categories with which he wrought,--"principle," "cause," "form," "matter," "potency," "act," "subject," were those of the Stagirite, and were open, therefore, to the same charge of unfruitfulness. On the other hand, while the outward form of Bruno's philosophy, and to a certain extent its matter also, were essentially Aristotelian, the spirit which infused it all was not so; the emotion and enthusiasm with which he wrote savoured rather of the fire of Plato than of the logical mind of his successor; and throughout, the new conception of nature and of mind which belongs to modern philosophy was struggling to the light. From his Platonist masters Bruno had learned that the Highest or First Principle was unknowable to man, being beyond the reach of his senses and of his understanding alike: a complete systematisation of knowledge was therefore impossible. A philosophy of nature had to seek only for physical (_i.e._ real or "immanent") causes or principles; these might depend, indeed, upon the highest and first principle or cause, but the dependence was not so close that the knowledge of the former gave us knowledge of the latter: no single system of knowledge could embrace both. Knowing the universe, we yet knew nothing of the essence or substance of its first cause, any more than that of the sculptor Apelles could be inferred from the statue he had made. The things of nature, although effects of the divine operation, became the remotest accidents, when regarded as means to the knowledge of the divine supernatural Essence. "We have still less ground for knowing it than for knowing Apelles from his finished statues, for all of these we may see, and examine, part by part, but not the great and infinite effect of the divine potency."[249] The First Principle is, therefore, the concern of the moralist and of the theologian, as revealed to them by the gods, or declared to them through the inspired knowledge of diviner men and of the prophets. On the other hand, in the universe we have the infinite image of God, and it is, therefore, possible through it to obtain an approximate knowledge of Him: "the magnificent stars and shining bodies, which are so many inhabited worlds, and animate beings or deities, worlds similar to that which contains ourselves, must depend, since they are composite and capable of dissolution, upon a principle and cause; and consequently, by their greatness,