Allusion allows readers to remember a text they already know.
<h3>What allusion?</h3>
It's a figure of speech.
It's a reference.
It is a reference to things or places known to the reader.
The allusion in the text can be seen in the expression "I pledge allegiance to the flag," which is a sentence present in the "Pledge of Allegiance," which is a text known to students. With this allusion, the reader has a reference to a text that he or she already knows and this makes the reading more pleasant and understandable.
The question above can be seen more harmoniously in the attached image.