Definition of "untransportable"

But Truth is such a flyaway, such a slyboots, so untransportable and unbarrelable a commodity, that it is as bad to catch as light.

1838 July 24, Ralph Waldo Emerson, “Literary Ethics. An Oration Delivered before the Literary Societies of Dartmouth College, July 24, 1838”, in J[ames] E[lliot] Cabot, editor, Nature, Addresses, and Lectures (Emerson’s Complete Works; I), Riverside edition, London: The Waverley Book Company, published 1883, page 166