Hath any Commentator well accounted for the Limitation which an antient Critic hath set to the Drama, which he will have contain neither more nor less than five acts? Or hath any one living attempted to explain, what the modern Judges of our Theatres mean by that Word low; by which they have happily succeeded in banishing all Humour from the Stage, and have made the Theater as dull as a Drawing-room? Upon all these Occasions, the World seems to have embraced a Maxim of our Law, viz. Cuicunque in Arte sua perito credendum est*: For it seems, perhaps, difficult to conceive that any one should have had enough of Impudence, to lay down dogmatical Rules in any Art or Science without the least Foundation. In such Cases, therefore, we are apt to conclude, there are sound and good Reasons at the Bottom, though we are unfortunately not able to see so far.
Now, in reality, the World have paid too great a Compliment to Critics, and have imagined them Men of much greater Profundity than they really are. From this Complaisance, the Critics have been emboldened to assume a Dictatorial Power, and have so far succeeded, that they are now become the Masters, and have the Assurance to give Laws to those Authors, from whose Predecessors they originally received them.
...For these Critics being Men of shallow Capacities, very easily mistook mere Form for Substance. They acted as a Judge would, who should adhere to the lifeless Letter of the Law, and reject the Spirit. Little Circumstances which were, perhaps, accidental in a great Author were, by these Critics, considered to constitute his chief Merit, and transmitted as Essentials to be observed by his Successors. To these Encroachments, Time and Ignorance, the two great Supporters of Imposture, gave Authority; and thus, many Rules for good Writing have been established, which have not the least Foundation in Truth or Nature; and which commonly serve for no other purpose than to curb and restrain Genius, in the same Manner as it would have restrained the Dancing-master, had the many excellent Treatises on that Art laid it down as an essential Rule, that every Man must dance in Chains.
- from The History of Tom Jones, 186. The Latin phrase means "Anyone expert in his profession should be believed."
