One of the Torah’s signature literary techniques is the use of textual echoes: the repetition of roots, words, or phrases that call us back to an earlier moment in the text.  The echo establishes an associative link between the earlier passage and the latter, and encourages us to consider comparisons between two different sections of the Torah.  In Parashat Vayehi we are given the epitome of all echoing phrases, one that became a symbol for the power of echoing itself.