The claim that English is not accepted by any finite-state automaton can only be supported by showing that every grammar for English has center- embedding to an unbounded depth (see Levelt 2008: 20–23 for an exposition and proof of the relevant theorem, originally from Chomsky 1959). But even depth-3 center-embedding of clauses (a clause interrupting a clause that itself interrupts a clause) is in practice extraordinarily hard to process. Hardly anyone can readily understand even semantically pl