We must wish that it were in our power, when we make observations upon nature, or when we read the reflections of others, to arrange our thoughts so as to be ready when we want to reason or invent. When cards are dealt to us, we can sort our hand according to the known probabilities of the game, and a new arrangement is easily made when we hear what is trumps.
In collecting and sorting observations, Dr. Franklin particularly excelled; therefore we may safely continue to take him for our example. Wherever he happened to be, in a boat, in a mine, in a printer's shop, in a crowded city, or in the country, in Europe or America, he displays the same activity of observation. When any thing, however trifling, struck him which he could not account for, he never rested till he had traced the effect to its cause. Thus, after having made one remark, he had fresh motive to collect facts, either to confirm or refute an hypothesis; his observations tending consequently to some determinate purpose, they were arranged in the moment they were made, in the most commodious manner, both for his memory and invention; they were arranged either according to their obvious analogies, or their relation to each other as cause and effect. He had two useful methods of judging of the value of his own ideas; he either considered how they could be immediately applied to practical improvements in the arts, or how they could lead to the solution of any of the great problems in science. Here we must again observe, that judgment saved the labour of memory. A person, who sets about to collect facts at random, is little better than a magpie, who picks up and lays by any odd bits of money he can light upon, without knowing their use.
Miscellaneous observations, which are made by those who have no philosophy, may accidentally lead to something useful; but here we admire the good fortune, and not the genius, of the individuals who make such discoveries: these are prizes drawn from the lottery of science, which ought not to seduce us from the paths of sober industry. How long may an observation, fortunately made, continue to be useless to mankind, merely because it has not been reasoned upon! The trifling observation, that a straight stick appears bent in water, was made many hundred years before the reason of that appearance was discovered! The invention of the telescope might have been made by any person who could have pursued this slight observation through all its consequences.