Although he didn't articulate it as thoroughly as Stanislavski, Shakespeare touches on the subject of how actors should conduct themselves on stage. It can be found in Hamlet, Act 3, Scene 2, Lines 1-45 (the advice to the players):

Speak the speech, I pray you, as I pronounced it to you, trippingly on the tongue: but if you mouth it, as many of your players do, I had as lief the town-crier spoke my lines. Nor do not saw the air too much with your hand, thus, but use all gently; for in the very torrent, tempest, and, as I may say, the whirlwind of passion, you must acquire and beget a temperance that may give it smoothness. O, it offends me to the soul to hear a robustious periwig-pated fellow tear a passion to tatters, to very rags, to split the ears of the groundlings, who for the most part are capable of nothing but inexplicable dumbshows and noise: I would have such a fellow whipped for o'erdoing Termagant; it out-herods Herod: pray you, avoid it.

...

Be not too tame neither, but let your own discretion be your tutor: suit the action to the word, the word to the action; with this special o'erstep not the modesty of nature: for any thing so overdone is from the purpose of playing, whose end, both at the first and now, was and is, to hold, as 'twere, the mirror up to nature; to show virtue her own feature, scorn her own image, and the very age and body of the time his form and pressure. Now this overdone, or come tardy off, though it make the unskilful laugh, cannot but make the judicious grieve; the censure of the which one must in your allowance o'erweigh a whole theatre of others. O, there be players that I have seen play, and heard others praise, and that highly, not to speak it profanely, that, neither having the accent of Christians nor the gait of Christian, pagan, nor man, have so strutted and bellowed that I have thought some of nature's journeymen had made men and not made them well, they imitated humanity so abominably.

...

O, reform it altogether. And let those that play your clowns speak no more than is set down for them; for there be of them that will themselves laugh, to set on some quantity of barren spectators to laugh too; though, in the mean time, some necessary question of the play be then to be considered: that's villanous, and shows a most pitiful ambition in the fool that uses it. Go, make you ready.

So Shakespeare's proto-Stanislavskian advice to his actors is essentially as follows:

• Speak clearly and distinctly without indulgent over-enunciation.

• Be judicious with gesture so that you appear neither stiff nor overly frantic.

• When passion takes you in the moment, do not let your emotion go over-the-top into something presentational.

• Don't be too timid, but let your own emotions and the literal meaning of the words guide you toward honest human feeling.

• A perfect performance is one that is indistinguishable from realistic human emotion.

• Avoid excessive comic ad-libbing that distracts from the narrative being presented.

It's short and simple, but it is concerned with helping actors create more realistic performances. Shakespeare outlines well the results he would like to see, but provides no guidelines on how actors can use their time to improve their abilities toward Shakespeare's standards. Stanislavski, on the other hand, gives us tools and exercises that help us to grow toward the very virtues that Shakespeare asks us to apply.

There is only one Constantin Stanislavski, but I hope you find this example satisfactory.