The letter zayin looks quite similar to its neighbor, the letter vav. Tall and straight, a simple vertical line, the vav (equivalent to the number six) represents the visible world (corresponding to six sides: front, back, right, left, up and down). The zayin, which looks like a crowned vav, has the numerical value of seven and represents, according to Kabbalah, the natural order.
Seven represents the natural order as represented by the seven days of creation. One way of understanding the power of seven is to imagine a box. A box has six sides including the top and the bottom, the seventh “dimension” of a box is the empty matter inside.
As a representative of nature, is it any wonder that zayin is the first letter of the word zera, seed? A seed represents ultimate completion in nature, for everything a plant needs to grow is already contained within it. It is also the first letter of the word zan, which means sustainer and is a reference to God who provides the world with grain for food. The letter zayin is so closely tied to nature that it even looks like a flower newly sprouted from the ground.
The Hebrew noun zayin, however, actually translates as weapon, reminding the world that since the curse of Adam, it is natural for humankind to “struggle” for his/her sustenance.
Bibliographical acknowledgment: The Wisdom In The Hebrew Alphabet: The Sacred Letters as a Guide to Jewish Deed and Thought. By Rabbi Michael L. Munk, Mesorah Publications, 1983.