Johnson claims that with Shakespeare's histories, the unites of time, place, and action are largely irrelevant since, in his plays, "the changes of action be so prepared as to be understood, that the incidents be various and affecting, and the characters consistent, natural and distinct. No other unity is intended, and therefore none is to be sought."
With his other works (comedies and tragedies), Johnson adds that Shakespeare sustains the unity of action; even when the events are out of order or superfluous, Shakespeare does stick to Aristotle's linear progression of having a discernible beginning, middle, and end.
In terms of time and place, the law of the unities states that for a play to be credible (believable), the events of the play should be limited to a particular place and the time limited to 24 hours. Otherwise, the audience will have trouble suspending disbelief (believing the events could happen) which is to say the audience will have trouble forgetting that they are watching a play. Johnson counters this by saying that all plays are plays:
The truth is, that the spectators are always in their senses, and know, from the first act to the last, that the stage is only a stage, and that the players are only players.
Therefore, these limitations based on being credible to the audience can not be applied. Johnson also adds that the pleasure of watching theater is that it is fictional; it is not necessary that they have to believe it could happen: "The delight of tragedy proceeds from our consciousness of fiction; if we thought murders and treasons real, they would please no more."
Johnson adds that "the unities of time and place are not essential to a just drama . . . " and that simply sticking to the rules does not make a drama good. That which makes Shakespeare's plays "just" is how deeply they apply to human nature. This is perhaps the most significant praise in the essay. For Johnson, there is something true and universal about Shakespeare's appreciation of human nature and this is what makes him timeless. Johnson notes that: "This therefore is the praise of Shakespeare, that his drama is the mirror of life . . . "
Johnson does fault Shakespeare for focusing too much on the convenience of the storyline, therefore ignoring the use of his plays as instruction (showing how good could/should triumph over evil). But overall, it is Shakespeare's ability to copy nature (art imitating life), being believable or unbelievable, that makes any of Shakespeare's so called faults irrelevant.