Dennis Danielson's excellent book is an exploration of the world of seventeenth-century cosmological speculation and its connections to broader philosophical and religious questions. It is at once a survey of the key issues and a wide range of theories then current, a corrective to old historical clichés, and a lively and reverent discussion of Milton that takes him seriously both as a great poet and as a critical thinker. Danielson carefully unravels and explores Milton's cosmological views. He provides a deeply compelling interpretation and situates it within a broader world of thought.

Danielson introduces the anachronistic term ‘multiverse’, forcing us to think of cosmological debate in Milton's time in unfamiliar ways, and to avoid familiar clichés and binaries such as Copernicanism versus Ptolemaism, which oversimplify a much more complex (and interesting) past. Milton's view was one of a host of different pictures of existence based on geocentric, geostatic, heliocentric and even multi-centric views, in a world where the question of position was tied to questions of size, significance, relation and influence.

Danielson bases his picture of Milton's ‘multiverse’ on cosmological descriptions and creation narratives in Paradise Lost (1667) and The Christian Doctrine (discovered in 1823). Matter is created ex Deo, rather than ex nihilo. God first created matter, boundless and formless, from a part of his own infinity. Then he circumscribed a portion of this chaos of unformed matter, within which he created our universe. Milton locates Heaven and Hell outside our own universe. These other domains too are demarcated within Chaos, and travel – at least for angels and demons – is possible between them. Consequently, matter, as created from a part of God, cannot be ignoble by nature. There is a great vibrancy and vitality at play in Milton's view of existence that Danielson captures expertly.

Within our universe Milton's cosmological views are non-committal. Milton celebrates Galileo in Paradise Lost without fully committing to a Galilean view. Danielson takes the time to describe the world of astronomical thought in Milton's day, showing that Milton was not unwise in being cautious. Danielson returns time and again to the wonderful astronomical discussion in Book 8 of Paradise Lost, which presents a variety of astronomical views in terms of a series of ‘what-if?’ questions that the angel Raphael puts to Adam. Here Milton is both astronomically non-committal and open, and he celebrates the possibilities of a set of cosmological questions not yet fully decided. ‘One of the glories of Milton’, Danielson notes, ‘is that, like other great poets, he permits us to see significant things afresh – perhaps even to see things we have never seen before’ (p. xiii).

Danielson provides an excellent and nuanced survey of the cosmological revolution as it was still in process. Chapter 1 provides the necessary background. Danielson breaks up the Ptolemaic–Copernican binary by introducing the variety of different views – Tycho Brahe's being one of the most important – that were accepted or rejected, in whole and in part, by Milton's contemporaries. The question was not, as Galileo had framed it, an either/or between Ptolemaism and the new, obviously correct, Copernicanism; rather there were a whole host of questions about different propositions and components of systems that were often rejected or accepted only piecemeal, rather than as part of a complete package.

Chapter 2 presents Danielson's argument that Milton's views can best be characterized as a ‘multiverse’. Introducing another useful anachronistic term, Chapter 3 characterizes the acceptance and rejection of components of various systems as a sort of cosmological ‘bricolage’. Danielson shows the various ways in which Milton's contemporaries cobbled together components of various systems as they formed their own views. A prime example is Thomas Digges, who, though a Copernican, maintained the Ptolemaic conception of a ‘two storey universe’ (p. 6) where the earthly domain is ignoble, and that above the Moon is divine.

Chapter 4 looks at Galileo's telescopic discoveries and their incredible import, and resistance to his Copernican conclusions, even from such a hero of the history of science as Bacon. This leads into Chapter 5, which shows the range of different cosmological pictures competing in Milton's day. Here and elsewhere Danielson shows that ‘Milton's apparent tentativeness about Copernican cosmology is … more deft and responsible than many have thought’ (p. x). Chapter 6 looks at the Sun, its symbolism and the implications that arise from moving it from the heavens to the centre of the cosmos, where, according to the Ptolemaic view, the universe's dross accumulates. Chapter 7, likewise, looks at the implications of the Earth's move from the centre. Danielson follows the threads of various lines of thought regarding nobility, symbolism, difference and relativity. Milton himself viewed the universe as a contingent (as created) but purposeful (as designed) place of life, potency and intercourse, where our world takes part in a vast cosmic dance.

The final chapter examines the implications of a non-geocentric cosmos. If Earth is just another planet, might other planets be earths? Danielson explores the astronomical, philosophical and theological implications of this question. Milton's cosmos (within the multiverse), Danielson argues, ‘is truly a universe’ with no difference between the earthly realm and the heavens (p. 195, original emphasis). Humanity is not fundamentally ignoble, but full of possibility for improvement, which is ‘crucial to Milton's theodicy’. ‘There is here no Gnostic shunning of the earthly or the physical’ (p. 197).

Danielson closes by discussing the teleological nature of Milton's cosmos. For Milton the universe and mankind were created for a purpose. Though we have limited vision and knowledge, our purpose is to strive for more, just as it is to strive to improve ourselves morally. In Paradise Lost we catch ‘fresh glimpses of a generative, unified, “single storey” Universe – and of “male and female light; / Which two great sexes animate the world”.’ These, Danielson argues ‘are about meaning, teleology, and also earthlings’ participation in the cosmos. At one level, at least for Milton and, I suspect, for many others too, that is above all what the cosmological revolution meant’ (p. 201).