202 ECONOMIC ESSAYS IN HONOR OF JOHN BATES CLARK 
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has been nearly ignored in economic theory for more than thirty 
years. Believing as I still do (and more strongly than ever) 
that the supply of loanable present concrete goods is a factor in 
true interest, and that such supply is in a specific way conditioned 
by cost, I venture once more to state (in four sentences) the bit 
of interest theory that I offered in 1889, 1890, 1891 as follows: 
The supply of immediately deliverable goods can almost 
instantly be increased by accelerating the processes of produc- 
tion. Accelerated production is more costly than production at 
usual speed. It is therefore the abnormal cost of accelerated 
production which normally limits the supply of immediately 
deliverable goods. Therefore the abnormal cost of accelerated 
production is a factor in the rate of true interest. 
The Austrian theory of interest occupied itself almost wholly 
with the stronger demand for present than for future goods. 
Later theory has not advanced much beyond it, or much beyond 
the Austrian explanation of the preference for the bird in hand. 
Stripped of various wrappings it amounted to an affirmation of 
impatience. We must have this, that and the other thing now, it 
was argued, because we are too childish to be able to wait. Every 
suggestion, even when entertained or advanced by Bohm-Bawerk 
himself, that the sooner we get capital goods in hand, the sooner 
we can begin to make them earn for us, was handled with extreme 
caution as likely to lead us into the bog of a “productivity 
theory” of interest. I have to admit quite shamelessly that I 
have never been able to take the impatience explanation seriously. 
[t is a rather extraordinary Hamlet with Hamlet left out. 
It is not because we cannot wait for a while that we demand 
capital goods now instead of tomorrow; it is because so often it 
happens that unless we can have capital goods now we must 
forego using them forever. The boy who wants an education 
in civil engineering must get it in youth or early manhood or 
never be a civil engineer. Opportunities come to the young 
lawyer, the young surgeon, the young chemist, which will not 
return. They come to the business man, to be held by “refusal” 
for a few days at the longest, then to be taken or for all time 
relinquished. 
This is just another way of saying that there are limits to that 
instant production of present goods by working over-time or 
harder. about which we were 3 moment ago discoursing. Increas-