קדיש Class Twenty. ד’ אותיות הוי’, מילוי ומילוי דמילוי equals 28. The idea of מילוי is discussed at length. It is lower but with a higher source. Explanation: real learning is in the discernment. The more detailed and precise one is, the truer they are, and they reveal a less dramatic, but deeper truth, than one who has clarity on the basic level only. In קדיש it is the same thing. The 28 letters and 28 words (the RaMaK adds the 28 words) are the development of שם הוי’ה from 4 to 10 to 28 and they reveal the G-dliness in the lowest of levels, like the darkness itself shining. Additionally the אלטער רבי says to pronounce the וי”ו in ולעלמי עלמיא bringing the total number of letters in יהא שמי’ה רבה to 29 (this is based on the spelling of שמי’ה with extra יו”ד). This וי”ו (is explained in the המשך תער”ב (see PDF to class # 15 ע’ א’תי”ז)) indicates bringing from the highest of the high to the lowest of the low. The actual prayer יהא שמי’ רבה וכו is discussed here. It is translated simply, and also more profoundly, it is the idea of bringing G-dliness to darkness and revealing the G-dliness of darkness itself. Different understandings of שמי’ רבה.
