This Curious and Excellent Piece, is a kind of _Introduction_ to the _Principles_ of the _Mechanical Philosophy_, explicating, by very Considerable Observations and Experiments, what may be, according to such Principles, conceived of the _Nature and Origine of Qualities and Forms_; the knowledge whereof, either makes or supposes the Fundamental and Useful part of _Natural Philosophy_. In doing of which, the Author, to have his way the clearer, writes rather for the _Corpuscularian_ Philosophers (as he is pleased to call them) in _General_, than any {192} _Party_ of them, keeping himself thereby disengaged from adopting an _Hypothesis_, in which perhaps he is not so throughly satisfied, and of which he does not conceive himself to be necessitated to make use here; and accordingly forbearing to employ Arguments, that are either grounded on, _or_ suppose _Atoms_, _or_ any _Innate Motion_ belonging to them; _or_ that the Essence of Bodies consists in Extension; _or_ that a _Vacuum_ is impossible; _or_ that there are such _Globuli Caelestes, or_ such a _Materia Subtilis_, as the _Cartesians_ imploy to explicate most of the _Phaenomena_ of Nature. The _Treatise_ consisting of a _Speculative_, and an _Historical_ part, the Author, with great modesty leaves the _Reader_ to judge; _Whether_ in the _First_ part he hath treated of the _Nature_ and _Origine of Forms and Qualities_ in a more Comprehensive way, than others; _Whether_ he has by fit Examples, and other means, rendred it more intelligible, than they have done: _Whether_ he has added any considerable number of Notions and Arguments towards the compleating and confirming of the proposed _Hypothesis_: _Whether_ he has with reason dismissed Arguments unfit to be relied on; and _Whether_ he has proposed some Notions and Arguments so warily, as to keep them from being liable to Exceptions and Evasions, whereto they were obnoxious, as others have proposed them. And, as to the _Second_ and _Historical_ part, he is enclin'd to believe that the _Reader_ will grant, he hath done that part of _Physicks_, he is treating of, some service, by strengthning the doctrines of the _New Philosophy_ (as 'tis call'd) by such particular Experiments, whose Nature and Novelty will render them as well Acceptable as Instructive. The _summe_ of the _Hypothesis_, fully and clearly explicated in the _First_ Part, is this; That all Bodies are made of _one Catholick matter_, common to them all, and differ but in _Shape, Size, Motion_ or _Rest_, and _Texture_ of the small parts, they consist off; from which {193} Affections of Matter, the _Qualites_, that difference particular Bodies, result: whence it may be rationally concluded, that one kind of Bodies may be transmuted into another; _that_ being in effect no more, than that one Parcel of the Universal Matter, wherein all Bodies agree, may have a _Texture_ produced in it, like the _Texture_ of some other Parcel of Matter, common to them both.