Dr. Edward Smith, an English Physiologist, in an address before the Royal Medical and Chirurgical Society, remarked that "tea increased waste in the body, excited every function, and was well fitted to cases where there was a superfluity of material in the system;--but is injurious to the under-fed, or where there is greater waste than supply." Dr. Smith recommended tea as a preventive of heat-appoplexy, and in cases of suspended animation, as from partial drowning. We have selected these expressions of opinion from among a large number of diverse character, for the purpose of illustrating the uncertainty of knowledge concerning tea. To recapitulate:-- Professor Johnston finds that tea exhilarates; excites to activity, produces wakefulness; yet it sooths, and it tranquilizes the vascular system; it lessens waste and saves food. Dr. Smith found tea to increase waste, and to be injurious where food is deficient; says tea excites every function,--which must include the vascular system. Dr. Hutchinson and Dr. Kane agree in the main. What is the meaning of such radical differences of view? We think they arise from three causes: First, tea affects different persons very differently; secondly, the subject has not received that careful study which it merits, and thirdly, there is a careless confounding of at least three classes of effects, and a confusion of terms in describing them. We feel an unaffected diffidence in criticising and endeavoring to improve upon the expressions of scientific men of honest purpose, but we may be pardoned for pointing the way to a more careful analysis of the merits and deficiencies of an article of diet used by so many millions of people. We find among the ordinary effects of tea-drinking: Exhilaration:--an elevation of feeling, a lightness of mood or spirits; a cheerfulness or even joy, which is compatible with rest. This effect may be entirely independent of pure stimulus, or of any disposition to mental or physical activity. Stimulation:--a quickening or rousing to action of any faculty, but as usually employed, an urging to action of bodily or mental powers. Sustaining:--enabling one to continue the expenditure of energy with less sense of fatigue, at the time, or afterwards. Refreshing:--relieving or reviving after exertion of any kind; reanimating, invigorating; contributing to rest after fatigue. Exciting:--in the sense of stimulation of brain and nervous system to higher tension, but not necessarily attended by disposition to labor or useful activity. Now some tea-drinkers find in the beverage exhilaration only, a lightness of mood, but they are disposed to rest and to revery, to simply a passive meditation, or an indulgence of the imagination. Others are stimulated to mental or to physical activity, and are sustained during such action. Afterwards they are refreshed when fatigued, by the same beverage.