According to Ramaz, it is fit to be called "Midrash haNe'elam" because "its topic is mostly the "neshamah" (an upper level of soul), the source of which is in "Beri'ah", which is the place of the upper Gan Eden; and it is written in the "Pardes" that drash is in "Beri'ah"... and the revealed midrash is the secret of externality, and "Midrash haNe'elam" is the secret of internality, which is the neshamah. And this derush is founded on the neshamah; its name befits it – "Midrash haNe'elam".