It is known that in the Aryan languages some of the oldest words are without gender; speaking grammatically, pater is not a masculine, nor mater a feminine; nor do the oldest words for river, mountain, tree, or sky, disclose any outward sign of grammatical gender. But though without any signs of gender, all ancient nouns expressed activity. The distinction of gender began, not with the introduction of masculine nouns, but with the setting apart of certain derivative suffixes for feminine words; thus when _bona_ was introduced, _bonus_ became masculine; when _puella_ could be applied to a girl, _puer_, which formerly meant both boy and girl, became restricted to the meaning of boy. Therefore, whenever it happens that we have a female representative of a natural phenomenon by the side of a male, the female may almost always be taken as the later form. This rule, which has been strictly applied to the name of Dyaus, dates from so remote a time that its origin is lost in the mists of ages. Dyaus, like _deva_, shining, comes from the root _div_ or _dyu_, but this root bifurcates at once. In the Rig-Veda forms derived from the base _div_ are masculine or feminine as the case may be, whilst those which are derived from _dyu_ are always masculine; thus _dyaus_ from _div_, is the firmament, the expanse above our heads, and is the later feminine form; whereas _dyaus_ from _dyu_, is the sky considered as a power, an active force, and is masculine, and consequently is the earlier conception. These two words, _dyaus_, nominative singular, and its base, _dyu_, being almost synonymous may be used indifferently. All vegetable cells are destined to become plants, though sometimes different plants, this, observation of nature teaches us. All verbal cells are destined to become words, though differing, that is, with different meanings; the small amount of philological study to which we have already devoted ourselves in these pages shows us this. All cells, whatever their nature, possess a transitive movement; the French word _éclater_ has the meaning of to disperse in brilliancy; if we imagine scintillations of light escaping from a central luminary we obtain the idea of a transitive luminous movement. Whilst a cell preserves its primary condition it is not possible to predict its future; no human intelligence could have foretold that the root _div_ and _dyu_ would produce the Sanscrit word deva, which means to shine, and deva would in time develop into deus, which now no longer means to shine, but God. It is a curious characteristic of Vedic Sanscrit that this uncertainty of meaning of such words as deva, which expresses equally the half physical and half spiritual intention, is an evidence of its rays having proceeded from the same source of light and heat.