I think that it is not Acton, although it expresses sentiments he might have uttered. The quote is, I think, with insignificant modifications, from Sir Henry Maine, in his ‘Village Communities’ (3rd ed., 1876) p. 238. In this lecture, Maine’s proposition is that the idea of progress has been received by the British from the Greeks and passed on to the Indians.
Sir Henry Maine, ‘Village Communities’ (3rd ed., 1876) p. 238.
“Whatever be the nature and value of that bundle of influences which
we call Progress, nothing can be more certain than that, when a
society is once touched by it, it spreads like a contagion. Yet, so
far as our knowledge extends, there was only one society in which it
was endemic; and putting that aside, no race or nationality, left
entirely to itself, appears to have developed any very great
intellectual result, except perhaps Poetry. Not one of those
intellectual excellencies which we regard as characteristic of the
great progressive races of the world — not the law of the Romans, not
the philosophy and sagacity of the Germans, not the luminous order of
the French, not the political aptitude of the English, not that
insight into physical nature to which all races have contributed —
would apparently have come into existence if those races had been left
to themselves. To one small people, covering in its original seat no
more than a handsbreadth of territory, it was given to create the
principle of Progress, of movement onwards and not backwards or
downwards, of destruction tending to construction. That people was the
Greek. Except the blind forces of Nature, nothing moves in this world
which is not Greek in its origin. A ferment spreading from that source
has vitalised all the great progressive races of mankind, penetrating
from one to another, and producing results accordant with its hidden
and latent genius, and results of course often far greater than any
exhibited in Greece itself. It is this principle of progress which we
Englishmen are communicating to India. We did not create it. We
deserve no special credit for it. It came to us filtered through many
different media. But we have received it; and as we have received it,
so we pass it on. There is no reason why, if it has time to work, it
should not develop in India effects as wonderful as in any other of
the societies of mankind."
(emphasis added)