Saussure’s idea of language (Lehman 1991).

"Saussure conceived of language as a system of signs rather than an
orderly procession of meanings. One of his key insights is that the
word dog has no intrinsic meaning: nothing in the word, its sound or
its shape on the page suggests a barking animal, any more than does
hund in German or chien in French. Language consists of signs, and
signs are not independent entities that can be studies in isolation:
signs can only be understood in relation to one another within a
larger linguistic system. The meaning of a sign is a function of its
difference from the others. Dog means what it does in English because
it is not hog or bog. And this is true for concepts as well. The
terms we use have meaning, Saussure reasoned, not because they
correspond to an external reality and not because they reflect ideas,
but because of their differentiation. It follows that the pairs of
any culturally determined binary opposition define themselves in
relation to one another (Lehman 1991, p. 94)."
Thus the internal consistency of Rig Veda does not matter to
comparative linguists. Word like ratha and chakra can be pulled out
and compared in isolation with objects found thousand of miles away in
completely different contexts.
Lehman, D. (1991). Signs of the times: deconstruction and the fall
of paul de man. New York: Poseidon Press. ISBN: 0-671-68239-3
M. Kelkar