Ocean waves are "emergent phenomena" that arise out of the complexity of forces active in a large body of water. Photo by Chris Potter.

The conclusions … depend on ideas that must first be well comprehended and which are now novel to the large majority of readers and unfamiliar to all. But those who care to brace themselves to a sustained effort need not feel much regret that the road to be traveled over is indirect, and does not admit of being mapped beforehand in a way they can clearly understand. It is full of interest on its own. It familiarizes us with curious laws of chance that apply to a vast diversity of social subjects. This part of inquiry may be said to run along a road on a high level, that affords wide views in unexpected directions, and from which easy descents may be made to totally different goals to those we have now to reach. I have a great subject to write upon, but feel keenly my literary incapacity to make it easily intelligible without sacrificing accuracy and thoroughness. (Pp. 2-3)
    Order in Apparent Chaos … I know of scarcely anything so apt to impress the imagination as the wonderful form of cosmic order expressed by the ‘Law of Frequency of Error’. The law would have been personified by the Greeks and deified, if they had known of it. It reigns with serenity and in complete self-effacement amidst the wildest confusion. The huger the mob, and the greater the apparent anarchy, the more perfect is its sway. It is the supreme law of Unreason. Whenever a large sample of chaotic elements are taken in hand and marshalled in the order of their magnitude, an unsuspected and most beautiful form of regularity proves to have been latent all along. The tops of the marshalled row form a flowing curve of invariable proportions; and each element, as it is sorted into place, finds, as it were, a pre-ordained niche, accurately adapted to fit it. If the measurement at any two specified Grades in the row are known, those that will be found at every other Grade, except towards the extreme ends, can be predicted in the way already explained, and with much precision.
    Problems in the Law of Error… All the properties of the Law of Frequency of Error can be expressed in terms of Q, or the Prob: Error, just as those of a circle can be expressed in terms of its radius. The visible Schemes are not, however, to be removed too soon from our imagination. It is always well to retain a clear geometric view of the facts when we are dealing with statistical problems, which abound with dangerous pitfalls, easily overlooked by the unwary, while they are cantering gaily along upon their arithmetic. The Laws of Error are beautiful in themselves and exceedingly fascinating to inquirers, owing to the thoroughness and simplicity with which they deal with masses of materials that appear at first sight to be entanglements on the largest scale, and of hopelessly confused description…

Galton, Francis. Natural Inheritance, Macmillan and Co. London, 1889, pp. 66-67.