The terms "agents" and "factors" of production were used concurrently for  
some time.  
  
In the original Palgrave (1894), there is an entry written by Edgeworth for  
"Agents of Production". There he writes. "To the second factor is sometimes  
applied the term _land_".  This entry is very useful in tracing change from  
"agents" to "factors". FYE quotes from Marshall's _Principles_: "it is  
perhaps best to say that there three factors of production".  Before that he  
quotes Mill's  "labour and natural agents".  
Interestingly in the same article FYE  translates from the German  
Boehm-Bawerk _Kapital and Kapitalzins_ pt ii p 83 "all production is the  
result of two and only two elementary agents of production, nature and  
labour". The translation by William A. Smart (Macmillan 1891) of the same  
text in BB's _The Positive Theory of Capital_ is the following "Thus all  
that we get in production is the result of two, and only two, elementary  
productive powers- Nature and Labour".  
  
Elsewhere in the same book Smart translates:  
  
"When we are told that capital assists in the production of wealth, and then  
again that it assists in the obtaining of wealth for its owner, we are apt  
to jump to the conclusion that the two phenomena are intimately and  
essentially connected, and that the one is the immediate result of the  
other-that capital can bring wealth to its owner because capital assists in  
the production of wealth. As a fact, Political Economy has taken up this  
idea only too readily and too completely. Captivated by the deceptive  
symmetry that exists between the three great factors of production-Nature,  
Labour, Capital-and the three great blanches of income-Rent, Wage, and  
Interest-the science, from Say's day till the present, has taught that these  
three branches of income are nothing else than the payment for the three  
factors of production, and that Interest in particular is nothing else than  
the compensation which capital receives for its productive services when the  
product is divided out among society. Propounded by various interest  
theories in various forms this idea has found its most concise and, at the  
same time, its most naive expression, in the well-known "Productivity  
theories"-those theories which explain interest directly as the natural  
fruit of a productive power peculiar to and resident in capital  
In like manner, in dealing with the particular markets of the productive  
factors or agents, we shall find that it is not by considering the special  
services that land renders to production, and the special conditions under  
which it renders them, or by considering the same problem with reference to  
labour or capital, that we shall worm out the secrets of the process of  
"distribution," but by considering that aspect under which all of these, and  
any other factors of production there may be, resemble each other."  
  
Equally Wicksteed in _The Common Sense of Political Economy_ (1910) writes:  
  
"In like manner, in dealing with the particular markets of the productive  
factors or agents, we shall find that it is not by considering the special  
services that land renders to production, and the special conditions under  
which it renders them, or by considering the same problem with reference to  
labour or capital, that we shall worm out the secrets of the process of  
"distribution," but by considering that aspect under which all of these, and  
any other factors of production there may be, resemble each other".  He  
starts in the introduction with factors or agents and then he uses the term  
factors of production.  
  
In Say's translation the term is "agents".  
  
Similarly in Laclor's Cyclopedia (1881) there is an entry by Charles  
Coquelin for "Agents, natural" but elsewhere Worthington C. Ford in the  
entry "Participation in profits" writes "factors of production".  
  
It seems to me that it was the influence of Alfred Marshall that made the  
change from agents to factors, but also he even in the 1920 edition uses  
occasionally both terms, e.g. in  Bk. vi ch ii."The amount of the thing and  
its price, the amounts of the several factors or agents of production used  
in making it, and their prices".  
  
Note: with the exception of the original Palgrave, for all other quotes I  
have used econlib.org's search facility.  
  
Nicholas J. Theocarakis