There is also an insidious suggestion, carrying a sinister note of discredit, that comes in from ethnological science at this point; which is adapted still further to derange the common man's faith in this received institution of ownership and its control of the material equipment of industry. To students interested in human culture it is a matter of course that this material equipment is a means of utilising the state of the industrial arts; that it is useful in industry and profitable to its owners only because and in so far as it is a creation of the current technological knowledge and enables its owner to appropriate the usufruct of the current industrial arts. It is likewise a matter of course that this technological knowledge, that so enables the material equipment to serve the purposes of production and of private gain, is a free gift of the community at large to the owners of industrial plant; and, under latterday conditions, to them exclusively. The state of the industrial arts is a joint heritage of the community at large, but where, as in the modern countries, the work to be done by this technology requires a large material equipment, the usufruct of this joint heritage passes, in effect, into the hands of the owners of this large material equipment. These owners have, ordinarily, contributed nothing to the technology, the state of the industrial arts, from which their control of the material equipment of industry enables them to derive a gain. Indeed, no class or condition of men in the modern community--with the possible exception of politicians and the clergy--can conceivably contribute less to the community's store of technological knowledge than the large owners of invested wealth. By one of those singular inversions due to production being managed for private gain, it happens that these investors are not only not given to the increase and diffusion of technological knowledge, but they have a well-advised interest in retarding or defeating improvements in the industrial arts in detail. Improvements, innovations that heighten productive efficiency in the general line of production in which a given investment is placed, are commonly to be counted on to bring "obsolescence by supersession" to the plant already engaged in that line; and therefore to bring a decline in its income-yielding capacity, and so in its capital or investment value.