The actor, doubtless, is as strongly tied down to the rules of Horace as the writer:
Si vis me flere, dolendum est Primum ipsi tibi----
He that feels not himself the passion he would raise, will talk to a sleeping audience: but this never was the fault of Betterton; and it has often amazed me to see those who soon came after him, throw out in some parts of a character, a just and graceful spirit, which Betterton himself could not but have applauded. And yet in the equally shining passages of the same character, have heavily dragged the sentiment along like a dead weight; with a long-toned voice, and absent eye, as if they had fairly forgot what they were about. If you have never made this observation, I am contented you should not know where to apply it.
"A farther excellence in Betterton, was, that he could vary his spirit to the different characters he acted. Those wild impatient starts, that fierce and flashing fire, which he threw into Hotspur, never came from the unruffled temper of his _Brutus_ (for I have more than once, seen a _Brutus_ as warm as Hotspur) when the Betterton Brutus was provoked, in his dispute with Cassius, his spirit flew only to his eye; his steady look alone supplyed that terror, which he disdained an intemperance in his voice should rise to. Thus, with a settled dignity of contempt, like an unheeding rock, he repelled upon himself the foam of Cassius. Perhaps the very works of Shakspeare will better let you into my meaning:
Must I give way, and room, to your rash choler? Shall I be frighted when a madman stares?
There is no terror, Cassius, in your looks! &c.
Not but in some part of this scene, where he reproaches _Cassius_, his temper is not under this suppression, but opens into that warmth which becomes a man of virtue; yet this is that _hasty spark_ of anger, which Brutus himself endeavours to excuse.
"But with whatever strength of nature we see the poet show, at once, the philosopher and the hero, yet the image of the actor's excellence will be still imperfect to you, unless language could put colours in our words to paint the voice with.
"_Et, si vis similem pingere, pinge sonum_, is enjoining an impossibility. The most that a _Vandyke_ can arrive at, is to make his portraits of great persons seem to _think_; a Shakspeare goes farther yet, and tells you _what_ his pictures thought; a Betterton steps beyond them both, and calls them from the grave, to breathe, and be themselves again, in feature, speech, and motion. When the skilful actor shows you all these powers at once united, and gratifies at once your eye, your ear, your understanding. To conceive the pleasure rising from such harmony, you must have been present at it! 'tis not to be told you!