One of Rashi’s comments in this week’s parashah highlights the rabbinic tradition of interpreting a feature of Hebrew script known as “אותיות חסירות ויתרות” (otiot haseirot v’yeteirot), “missing and extra letters.”  The Hebrew alphabet has no vowel letters, and in most Hebrew writing, the vowel notations (nekudot) are not included; we know how to pronounce words based on context and tradition.  But certain vowels are sometimes “carried” by a silent letter, either a vav (ו) or a yod (י).  In writing words with those vowels, common practice dictates whether they are written with the silent letter or not.  When the writing deviates from common practice, we get the phenomenon of “missing and extra letters,” known in Latin as “defective” and “plene scriptum.”  For our Rabbis, who presumed every letter in sacred scripture to have been carefully and intentionally selected, an extra or a missing letter was understood to be an encoded message, waiting to be deciphered.