解析エラーを避けるために、PHP 文字列内の引用符をエスケープするにはどうすればよいですか?

$text1 = 'From time to "time" this submerged or latent theater in 'Hamlet'
           becomes almost overt. It is close to the surface in Hamlet's pretense of madness,
           the "antic disposition" he puts on to protect himself and prevent his antagonists
           from plucking out the heart of his mystery. It is even closer to the surface when
           Hamlet enters his mother's room and holds up, side by side, the pictures of the
           two kings, Old Hamlet and Claudius, and proceeds to describe for her the true
           nature of the choice she has made, presenting truth by means of a show.
           Similarly, when he leaps into the open grave at Ophelia's funeral, ranting in
           high heroic terms, he is acting out for Laertes, and perhaps for himself as well,
           the folly of excessive, melodramatic expressions of grief.";

$text1 = 'From time to \"time\" this submerged or latent theater in 'Hamlet'
...

$text1 = 'From time to "time"';

$heredoc = <<<term
This is a long line of text that include variables such as $someVar
and additionally some other variable $someOtherVar. It also supports having
'single quotes' and "double quotes" without terminating the string itself.
heredocs have additional functionality that most likely falls outside
the scope of what you aim to accomplish.
term;