The comparison particle is the word or construction conveying resemblance between the terms. Familiar tools include kāf (كـ), kaʾanna (كَأَنَّ), and sometimes verbs that imply comparison.
Kāf directly signals “like” in “Knowledge is like light.” Kaʾanna may add the flavor of an imagined state. The particle alone does not complete the analysis: one must still identify the compared terms and intended quality.