ubjectively
so--they cannot have independence as presented to our consciousness; and
this is the only kind of independence with which we are concerned. And
here, before leaving these illustrations, and especially this last one,
let us not omit to notice how clearly they exhibit that increasingly
active _consensus_ of the sciences which characterises their advancing
development. Besides finding that in these later times a discovery in
one science commonly causes progress in others; besides finding that a
great part of the questions with which modern science deals are so mixed
as to require the co-operation of many sciences for their solution; we
find in this last case that, to make a single good observation in the
purest of the natural sciences, requires the combined assistance of half
a dozen other sciences.

Perhaps the clearest comprehension of the interconnected growth of the
sciences may be obtained by contemplating that of the arts, to which it
is strictly analogous, and with which it is inseparably bound up. Most
intelligent persons must have been, at one time or other, struck with
the vast array of antecedents pre-supposed by one of our processes of
manufacture. Let him trace the production of a printed cotton, and
consider all that is implied by it. There are the many successive
improvements through which the power-looms reached their present
perfection; there is the steam-engine that drives them, having its long
history from Papin downwards; there are the lathes in which its cylinder
was bored, and the string of ancestral lathes from which those lathes
proceeded; there is the steam-hammer under which its crank shaft was
welded; there are the puddling-furnaces, the blast-furnaces, the
coal-mines and the iron-mines needful for producing the raw material;
there are the slowly improved appliances by which the factory was built,
and lighted, and ventilated; there are the printing engine, and the die
house, and the colour laboratory with its stock of materials from all
parts of the world, implying cochineal-culture, logwood-cutting,
indigo-growing; there are the implements used by the producers of
cotton, the gins by which it is cleaned, the elaborate machines by which
it is spun: there are the vessels in which cotton is imported, with the
building-slips, the rope-yards, the sail-cloth factories, the
anchor-forges, needful for making them; and besides all these directly
necessary antecedents, each of them involving m