ceffary to give plaufibility to a hypothetical theory, are likely to furnish, in time, the materials of a jufter system.

Some of the followers of Lord Bacon have, I think, been led, in their zeal for the method of induction, to cenfure hypothetical theories with too great a degree of feverity. Such theories have certainly been frequently of ufe, in putting philofophers upon the road of discovery. Indeed, it has probably been in this way, that moft difcoveries have been made; for although a knowledge of facts must be prior to the formation of a just theory, yet a hypothetical theory is generally our beft guide to the knowledge of useful facts. If a man, without forming to himself any conjecture concerning the unknown laws of nature, were to fet himself merely to accumulate facts at random, he might, perhaps, ftumble upon fome important difcovery; but by far the greater part of his labours would be wholly ufelefs. Every philofophical inquirer, before he begins a fet of experiments, has fome general principle in his view, which he fufpects to be a law of nature: and although his conjectures may be often wrong, yet they serve to give his inquiries a particular direction, and to bring under his eye a number of facts which have a certain relation to each other. It has been

"Recte fiquidem Plato, "Qui aliquid quærit, id ipfum, quod "quærit, generali quadam notione comprehendit : aliter, qui fieri "poteft, ut illud, cum fuerit inventum, agnofcat?" Idcirco quo "amplior et certior fuerit anticipatio noftra; eo magis directa et "compendiofa erit inveftigatio."

De Aug. Scient. lib. v. cap. 3.

often

often remarked, that the attempts to discover the philofopher's ftone, and the quadrature of the circle, have led to many useful discoveries in chemistry and methematics. And they have plainly done fo, merely by limiting the field of obfervation and inquiry, and checking that indifcriminate and defultory attention which is fo natural to an indolent mind. A hypothe. tical theory, however erroneous, may answer a fimilar purpose. "Prudens interrogatio," (fays Lord Bacon,)" eft dimidium fcientiæ. Vaga enim experi"entia et fe tantum fequens mera palpatio eft, et "homines potius ftupefacit quam informat." What, indeed, are Newton's queries, but fo many hypothefes which are propofed as fubjects of examination to philofophers? And did not even the great doctrine of gravitation take its firft rife from a fortunate conjecture?

A

While, therefore, we maintain, with the followers of Bacon, that no theory is to be admitted as proved, any father than it is fupported by facts, we should, at the fame time, acknowledge our obligations to those writers who hazard their conjectures to the world with modefty and diffidence. And it may not be improper to add, that men of a systematizing turn are not now fo ufelefs as formerly; for we are already poffeffed of a great ftock of facts; and there is fcarcely any theory fo bad as not to bring together a number of particulars which have a certain degree of relation or analogy to each other.

The foregoing remarks are applicable to all our various ftudies; whether they are conducted in the way of reading, or of obfervation. From neither of these

these two sources of information can we hope to derive much advantage, unless we have fome general principles to direct our attention to proper objects.

With respect to observation, some farther cautions may be useful; for in guarding against an indifcrimi. nate accumulation of particulars, it is poffible to fall into the oppofite extreme, and to acquire a habit of inattention to the phenomena which present themfelves to our fenfes. The former is the error of men of little education; the latter is more common among men of retirement and study.

One of the chief effects of a liberal education, is to enable us to withdraw the attention from the prefent objects of our perceptions, and to dwell at plea. fure on the past, the abfent, or the future. But when we are led to carry these efforts to an excess, either from a warm and romantic imagination, or from an anxious and fanguine temper, it is easy to see that the power of observation is likely to be weakened, and habits of inattention to be contracted. The fame effect may be produced by too early an indulgence in philofophical purfuits, before the mind has been prepared for the study of general truths, by exercising its faculties among particular objects, and particular Occurrences. In this way, it contracts an averfion to the examination of details, from the pleasure which it has experienced in the contemplation or in the difcovery of general principles. Both of these turns of thought, however, prefuppofe a certain degree of observation; for the materials of imagination are fupplied by the fenfes; and the general truths which occupy the philofopher, would be wholly unintelligible

to him, if he was a total ftranger to all experience with respect to the course of nature and of human life. The obfervations, indeed, which are made by men of a warm imagination, are likely to be innaccu rate and fallacious; and thofe of the fpeculative philofopher are frequently carried no farther than is neceffary to enable him to comprehend the terms which relate to the subjects of his reasoning; but both the one and the other muft have looked abroad occafion. ally at nature, and at the world; if not to ascertain facts by actual examination, at least to store their minds with ideas.

The metaphyfician, whofe attention is directed to the faculties and operations of the mind, is the only man who poffeffes within himself the materials of his fpeculations and reafonings. It is accordingly among this clafs of literary men, that habits of inattention to things external have been carried to the greatest

extreme.

It is obferved by Dr. Reid, that the power of reflexion, (by which he means the power of attending to the subjects of our consciousness,) is the last of our intellectual faculties which unfolds itself; and that in the greater part of mankind it never unfolds itfelf at all. It is a power, indeed, which being fubfervient merely to the gratification of metaphyfical curiofity, it is not effentially neceffary for us to poffefs, in any confiderable degree. The power of obfervation, on the other hand, which is neceffary for the prefervation even of our animal existence, discovers itself in infants long before they attain the ufe of fpeech; or rather I should have faid, as foon as they come into

the

the world and where nature is allowed free fcope, it continues active and vigorous through life. It was plainly the intention of nature, that in infancy and youth it fhould occupy the mind almost exclusively, and that we should acquire all our neceffary information before engaging in fpeculations which are less effential and accordingly this is the history of the intellectual progress, in by far the greater number of individuals. In confequence of this, the difficulty of metaphyfical researches is undoubtedly much increafed; for the mind being conftantly occupied in the earlier part of life about the properties and laws of matter, acquires habits of inattention to the fubjects of confcioufnefs, which are not to be furmounted, without a degree of patience and perfeverance of which few men are capable: but the inconvenience would evidently have been greatly increased, if the order of nature had, in this refpect, been reverfed, and if the curiofity had been excited at as early a period, by the phenomena of the intellectual world, as by thofe of the material. Of what would have happened on this fuppofition, we may form a judg ment from thofe men who, in confequence of an exceffive indulgence in metaphyfical pursuits, have weakened, to an unnatural degree, their capacity of attending to external objects and occurrences. Few metaphyficians, perhaps, are to be found, who are not deficient in the power of obfervation: for, although a taste for fuch abstract fpeculations is far from being common, it is more apt, perhaps, than any other, when it has once been formed, to take an exclufive hold of the mind, and to shut up the other fources

Hh 2