But outside the limelit circle this period was one of rapid intellectual development. That the novel interest in the external world, typified in the sixteenth century by such new words as _analyse_, _distinguish_, _investigate_[44], expanded continuously during the next hundred years is suggested by the addition to our vocabulary of _inspect_, _remark_, and _scrutinize_, together with the modern meanings of _perception_ and _scrutiny_, which had meant up till then respectively ‘the collection of rents’ and ‘the taking of a vote.’ We also find a group of new words to describe the inherent conditions and qualities of external objects, such as _acid_, _astringency_, _cohesion_, _elasticity_, _equilibrium_, _fluid_ (as a noun), _intensity_, _polarity_, _pressure_, _spontaneous_, _static_, _temperature_, _tendency_, _tension_, _volatile_, besides the physical and impersonal meanings of _energy_ and _force_. The old verb to _discover_, which originally signified simply to ‘uncover’ or ‘reveal,’[45] was used attributively in the sixteenth century of travellers ‘discovering’ foreign lands and customs. Shortly after the Restoration the new metaphor, so it would seem, was itself applied metaphorically to the results of a chemical experiment, and in this way the ordinary modern meaning arose. The creation of the new word _gas_ by the Dutch chemist van Helmont marks a definite epoch in the evolution of the scientific outlook. He used it, however, to describe an occult principle—a sort of ultra-rarefied water—which he supposed to be contained in all matter. It was not until the last quarter of the eighteenth century that the word acquired its modern meaning of ‘matter in the condition of an aeriform fluid’, at which time the word _gaseous_ also appeared. _Ether_ (Greek ‘aithēr’, ‘the _upper_ air’ above the clouds), which had been practically a synonym for the Aristotelian _quintessence_[46], was now adopted to express the mechanical substitute for that spiritual medium required by modern science in order to explain the phenomenon of action at a distance. These are among the first attempts which were made to describe the outer world objectively—from its own point of view instead of from the point of view of divinity or of human souls; it is interesting, therefore, to reflect that the success achieved is really only a relative one, as all the words mentioned, with the possible exception of _gas_,[47] are in the first place metaphors drawn from human activities such as those of ‘cutting’, ‘stretching’, and ‘pulling’.