It is thus that Berkeley’s thought culminates in _Siris_, that _Chain of Philosophical Reflexions and Inquiries concerning the Virtues of Tar-water, and divers other subjects connected together and arising one from another_, which appeared in 1744. This little book made more noise at the time of its appearance than any of his books; but not because of its philosophy, which was lost in its medicinal promise to mankind of immunity from disease. Yet it was Berkeley’s last attempt to express his ultimate conception of the universe in its human and divine relations. When _Siris_ is compared with the book of _Principles_, the immense difference in tone and manner of thought shews the change wrought in the intervening years. The sanguine argumentative gladiatorship of the _Principles_ is exchanged for pensive speculation, which acknowledges the weakness of human understanding, when it is face to face with the Immensities and Eternities. Compare the opening sections of the Introduction to the _Principles_ with the closing sections of _Siris_. The contingent data of our experience are now felt to be insufficient, and there is a more or less conscious grounding of the Whole in the eternal and immutable Ideas of Reason. “Strictly, the sense knows nothing. We perceive, indeed, sounds by hearing and characters by sight. But we are not therefore said to understand them.... Sense and experience acquaint us with the course and analogy of appearances and natural effects: thought, reason, intellect, introduce us into the knowledge of their causes.... The principles of science are neither objects of sense nor imagination: intellect and reason are alone the sure guides to truth.” So the shifting basis of the earlier thought is found to need support in the intellectual and moral faith that must be involved in all reasonable human intercourse with the phenomena presented in the universe. The inadequate thought of God, as only a Spirit or Person supreme among the spirits or persons, in and through whom the material world is realised, a thought which pervades _Alciphron_, makes way in _Siris_ for the thought of God as the infinite omnipresent Ground, or final sustaining Power, immanent in Nature and Man, to which Berkeley had become accustomed in Neoplatonic and Alexandrian metaphysics. “Comprehending God and the creatures in One general notion, we may _say_ that all things together (God and the universe of Space and Time) make One Universe, or τὸ Πᾶν. But if we should say that all things make One God, this would be an erroneous notion of God; but would not amount to atheism, as long as Mind or Intellect was admitted to be τὸ ἡγεμονικόν, or the governing part.... It will not seem just to fix the imputation of atheism upon those philosophers who hold the doctrine of τὸ Ἕν.” It is thus that he now regards God. Metaphysics and theology are accordingly one.