In the light of these considerations it seems feasible to indicate both the congruence and the distinction between the two categories of assets a little more narrowly than was done above. Both are assets,--that is to say, both are values determined by a capitalisation of anticipated income-yielding capacity; both depend for their income-yielding capacity on the preferential use of certain immaterial factors; both depend for their efficiency on the use of certain material objects; both may increase or decrease, as assets, apart from any increase or decrease of the material objects involved. The tangible assets capitalise the preferential use of technological, industrial expedients,--expedients of production, dealing with the facts of brute nature under the laws of physical cause and effect,--this preferential use being secured by the ownership of material articles employed in the processes in which these expedients are put into effect. The intangible assets capitalise the preferential use of certain facts of human nature--habits, propensities, beliefs, aspirations, necessities--to be dealt with under the psychological laws of human motivation; this preferential use being secured by custom, as in the case of old-fashioned good-will, by legal assignment, as in patent or copyright, by ownership of the instruments of production, as in the case of industrial monopolies.[10] * * * * * Intangible assets are capital as well as tangible assets; that is to say, they are items of capitalised wealth. Both categories of assets, therefore, represent expected "income-streams" which are of such definite character as to admit of their being rated in set terms per cent. per time unit; although the expected income need not therefore be anticipated to come in an even flow or to be distributed in any equable manner over a period of time. The income-streams to be so rated and capitalised are associated in such a manner with some external fact (impersonal to their claimant), whether material or immaterial, as to permit their being traced or attributed to an income-yielding capacity on the part of this external fact, to which their valuation as a whole may be imputed and which may then be capitalised as an item of wealth yielding this income-stream. Income-streams which do not meet these requirements do not give rise to assets in the accepted sense of the term, and so do not swell the volume of capitalised wealth.