Notwithstanding a passing observation of Dr. Tyndall's that "this power of pondering facts is one with which the ancients could be but imperfectly acquainted," some readers will be struck by the thought that it forms the nearest approach which can be made by any inductive discoverer to the old philosophical method of Dialectic. Janet says, in a volume to which those who have not encountered it will thank me for introducing them, "La dialectique logique dans Platon est parfaitement conforme aux lois de la raison. Elle ne sert qu'à réfuter les idées fausses, ou à éclaircir les idées données antérieurement par une sorte de synthèse, qui, suivant les uns, n'est que le progrès de la généralisation, et, selon nous, est le progrès de l'intuition." (Études sur la Dialectique dans Platon et dans Hegel, p. 393.) For a more complete appreciation of what is here stated in few words, the student should peruse pp. 244, seq. The account given by Janet appears in some measure to coincide with Dr. Tyndall's idea, though perhaps the word "Intuition" might be more entirely approved by Schelling or Coleridge than by any Physicist. Be this as it may, Dr. Tyndall's outline of the Inductive process in its highest form is evidently one which describes the prerogative of Genius--the exercise of Imagination as distinguished from Fancy--the child, that is, of Reason, rather than a stray bantling of sportive wit. To bring his general conception within the grasp of every-day workers, and describe a procedure which may be adopted as a kind of practical rule or maxim, let us look at this subject in the following manner. Suppose we take the example of a great idea; that, for instance, of the constitution of Great Britain, or any other nation which subsists in tolerable freedom from revolutionary change. There are clearly two elements involved--one, Permanence; the other, Progress. These, in the actual working constitution, form its factors, or moments (as they may be better termed); and in the idea or mental representation of the same, we may liken them to complementary colours in the spectrum, which appear separately contrasted in tint, but blend together in a wave of white light. Now, our analysing faculty of mind is, in point of fact, our intellectual prism. It separates each bright and strong idea into elements so antagonistic as to be apparently incompatible. Like clear yellow and shadowy violet, one component seems excellent in beauty, another its foil or opposite. To one class of minds truth consists in Permanence, and Progress is a note of evil omen. Of another class the contradictory is true. The real statesman alone knows that their blending is a question of measure and degree, of human affairs,--time, circumstance, and opportunity.