Others again are nervously excited and cannot rest or sleep; but are too "nervous," as they express it, to set about any formal task, especially of a mental character. We have known tea-drinkers, too, who after a hard day's toil, could drink two or three cups of strong tea and lie down to sleep for the night as quietly as babes are expected to--but do not. It must be evident that each person should observe the effects of tea upon himself or herself and be governed accordingly. Tea is a poison to some temperaments, and so are strawberries. Tea will cure a headache or may produce one; will dispose to rest or excite to action. We will sum then by conceding that all our quoted authorities are right in their conclusions, if limited to a limited class of tea-drinkers, and all are wrong, in a very broad application. Theine is the one constant agency in the effects of tea. It is present in teas that are devoid of essential oils--so far as the senses go--and it then still refreshes, stimulates, sustains, and even exhilarates, by actual experiment. The feeling of "comfort," attributed by some writers to the hot water of the tea, may be also enjoyed by drinking cold tea, which is no less refreshing in hot weather. The high-flavored essential oils (strictly oils which evaporate at very moderate temperatures) of Formosa teas seem to take part in the superior exhilarating or almost intoxicating effects of the choice varieties, but we have no certain proof of the fact; while the more intoxicating and stimulating, as well as deleterious, green teas possess very little, if any, of these pleasant oils. It seems to be an authodox opinion among physiologists that tea contributes nothing towards support of the human system; that it only rouses it into action, an effect which should, consistently, be followed by corresponding reaction and depression, which plainly is not the case. This hypothesis leaves the enquiring layman in a dilemma. Tea must either enable the system to draw more heavily or more economically upon the resources afforded by recognized food, or it is itself nutriment. Otherwise, an established principle of physics--that there can be no expenditure of energy without correlative cost--would be subverted. As tea is admitted upon experience to be most useful, and most craved by mankind, where the supply of food is insufficient; and as it is known to refresh and sustain in large degree in the absence of any food whatever, there is fair ground for the opinion, however heterodox, that tea directly affords nutriment to the human organism, and, possibly, to the brain and nerves in particular, as with phosphoric acid.