The practical value of the views here advanced (if they be admitted as true at all) would appear to be not inconsiderable, alike as regards politics or the well-being of the community, and medicine which deals with that of the individual. In the first case we see the rationale of compromise, and the equal folly of making experiments upon too large a scale, and of not making them at all. We see that new ideas cannot be fused with old, save gradually and by patiently leading up to them in such a way as to admit of a sense of continued identity between the old and the new. This should teach us moderation. For even though nature wishes to travel in a certain direction, she insists on being allowed to take her own time; she will not be hurried, and will cull a creature out even more surely for forestalling her wishes too readily, than for lagging a little behind them. So the greatest musicians, painters, and poets owe their greatness rather to their fusion and assimilation of all the good that has been done up to, and especially near about, their own time, than to any very startling steps they have taken in advance. Such men will be sure to take some, and important, steps forward; for unless they have this power, they will not be able to assimilate well what has been done already, and if they have it, their study of older work will almost indefinitely assist it; but, on the whole, they owe their greatness to their completer fusion and assimilation of older ideas; for nature is distinctly a fairly liberal conservative rather than a conservative liberal. All which is well said in the old couplet— “Be not the first by whom the new is tried, Nor yet the last to throw the old aside.” _Mutatis mutandis_, the above would seem to hold as truly about medicine as about politics. We cannot reason with our cells, for they know so much more than we do that they cannot understand us;—but though we cannot reason with them, we can find out what they have been most accustomed to, and what, therefore, they are most likely to expect; we can see that they get this, as far as it is in our power to give it them, and may then generally leave the rest to them, only bearing in mind that they will rebel equally against too sudden a change of treatment, and no change at all.