Why does it say that Hashem is very great? If Hashem cannot be defined by SIZE, then how can Hashem grow bigger or older?
In order to answer my friend's question, I picked up a Concordance.
One of the first entries for the word, "gadalta," is found in Parshat Toldot at the start of shlishi, the third aliya. Bereishit: 26:13: Vayigdal Ho'ish ...
In this context, Yitzchak Avinu wasn't growing spiritually. Instead, his r'chush - possessions, property, and portfolio - were all increasing! Yitzchak was becoming a "billionaire."
Let's look back at Tehillim:104:1. It's talking about the tz'va hashamayim; the wonders of the heavenly bodies.
Here, the words of praise mean that, Hashem, YOU possess a magnificent portfolio of astronomical proportions. The words are praising Hashem's possession, not His Self or His Middot. Hashem is GDL, great, in the sense of "Koneh Shamayim va'aretz." His property is Heaven and Earth.
Tangentially, this peirush directly relates to the piyyutim found in Birkat Yotzeir, Keil Adon and Eil Baruch GD'oL dei'ah. Through reciting this magnificent "Kapittel" on Rosh Hodesh, we remember the Creator and His creation.
In summary: we've illustrated what I call the "Concordance Technique for Parshanut" and have learned how to parse Psalm 104.
Years ago, I learned this technique from Rashi, Z"L. He often uses the TaNa"Ch itself as a resource when he explains a difficult word without using the Talmud, Midrash or Targum. Through this technique, Rashi both presents a peirush and teaches us how to create our own original peirushim.
BE"H I will illustrate Rashi's usage and a few of my own based upon following Rashi's methodology