Olam katan is a concept of Jewish philosophy

Jewish philosophy

Jewish philosophy , includes all philosophy carried out by Jews, or, in relation to the religion of Judaism. Jewish philosophy, until modern Enlightenment and Emancipation, was pre-occupied with attempts to reconcile coherent new ideas into the tradition of Rabbinic Judaism; thus organizing...

 that certain concepts mirror (in a kind of "microcosm

Macrocosm and microcosm

Macrocosm and microcosm is an ancient Greek Neo-Platonic schema of seeing the same patterns reproduced in all levels of the cosmos, from the largest scale all the way down to the smallest scale...

") the world as a whole (the "macrocosm".) Its use probably originates from the Midrash

Midrash

The Hebrew term Midrash is a homiletic method of biblical exegesis. The term also refers to the whole compilation of homiletic teachings on the Bible....

 (a section of the Midrash collection Otzar ha-Midrashim bears the title).

Man is compared to a "small world". This is mirrored in the Talmud

Talmud

The Talmud is a central text of mainstream Judaism. It takes the form of a record of rabbinic discussions pertaining to Jewish law, ethics, philosophy, customs and history....

ic statement that Adam's head

Human head

In human anatomy, the head is the upper portion of the human body. It supports the face and is maintained by the skull, which itself encloses the brain.-Cultural importance:...

 originated in the Land of Israel

Land of Israel

The Land of Israel is the Biblical name for the territory roughly corresponding to the area encompassed by the Southern Levant, also known as Canaan and Palestine, Promised Land and Holy Land. The belief that the area is a God-given homeland of the Jewish people is based on the narrative of the...

 and his trunk in Babylon

Babylon

Babylon was an Akkadian city-state of ancient Mesopotamia, the remains of which are found in present-day Al Hillah, Babil Province, Iraq, about 85 kilometers south of Baghdad...

 (Tractate: Sanhedrin). It is similarly echoed in the famous statement that killing one person is comparable to destroying a whole world (Mishnah

Mishnah

The Mishnah or Mishna is the first major written redaction of the Jewish oral traditions called the "Oral Torah". It is also the first major work of Rabbinic Judaism. It was redacted c...

 Sanhedrin 4:5).

In other Midrashic sources, the Tabernacle

Tabernacle

The Tabernacle , according to the Hebrew Torah/Old Testament, was the portable dwelling place for the divine presence from the time of the Exodus from Egypt through the conquering of the land of Canaan. Built to specifications revealed by God to Moses at Mount Sinai, it accompanied the Israelites...

is referred to as a "small world", with its various objects mirroring both different astronomical concepts and certain organs in the human body.