A living being has but a limited duration. It is born, develops, becomes organized, declines and dies. Through all the metamorphoses of form, of substance, and of energy, informing the whole course of its existence, there is a certain co-ordination, a certain harmony, which is necessary for the conservation of the individual. This harmony we call Life. Discord is disease,--the total cessation of the harmony is Death. When the form is profoundly altered and the substance changed, the transformation of energy no longer follows its regular course, the organism is dead. After death the colloids which have constituted the form of the living thing pass from their liquid state as "sols" into their coagulated state as "gels." The metamorphoses of form, substance, and energy still continue, but no longer harmoniously for the conservation of the individual, but in dis-harmony for its dissolution. Finally, the form of the individual disappears, the substance and the energy of the living being is resolved and dispersed into other bodies and other phenomena. {5} The results hitherto obtained from the study of life seem but inconsiderable when compared with the time and labour devoted to the question. Max Verworn exclaims, "Are we on a false track? Do we ask our questions of Nature amiss, or do we not read her answers aright?" Each branch of science at its commencement employs only the simpler methods of observation. It is purely descriptive. The next step is to separate the different parts of the object studied--to dissect and to analyse. The science has now become analytical. The final stage is to reproduce the substances, the forms, and the phenomena which have been the subject of investigation. The science has at last become synthetical. Up to the present time, biology has made use only of the first two methods, the descriptive and the analytical. The analytical method is at a grave disadvantage in all biological investigations, since it is impossible to separate and analyse the elementary phenomena of life. The function of an organ ceases when it is isolated from the organism of which it forms a part. This is the chief cause of our lack of progress in the analysis of life. It is only recently that we have been able to apply the synthetic method to the study of the phenomena of life. Now that we know that a living organism is but the arena for the transformation of energy, we may hope to reproduce the elementary phenomena of life, by calling into play a similar transformation of energy in a suitable medium. Organic chemistry has already obtained numerous victories in the same direction, and the rapid advance in the production of organic bodies by chemical synthesis may be considered the first-fruits of synthetic biology.