226 NATURE OF CAPITAL AND INCOME [Cmar. XIII

small sum, such as $1000, if allowed to accumulate, let us
say, at 4 per cent for 1000 years, could never actually
attain the theoretical magnitude. This is evident from
the fact that the theoretical sum would then amount to
over $100,000,000,000,000,000, which is so far in excess of
the total value of capital on this planet, as to be out of
the range of possibility. The reason the sum would fail
to accumulate as fast as theoretically required, aside from
fortuitous losses, lies in the reduction of the rate of interest
 which the very accumulation would bring about.
The administrators of such a fund, as the centuries passed
by, would find it increasingly difficult to obtain fields in
which to invest it, and their effort so to invest would have
the same effect in reducing the rate of interest realized on
the investments as is now felt by the national banks in
their pressure to buy government bonds.