Suares: Hay, no. 5, is the archetype of universal life. When it is conferred upon Dallet,
it allows it to play the game of existence, in partnership with the intermittent life-death process.
Four letters before, four letters after, life in the balance. God invented Life as the most efficient way to mediate between energies and explore developmental potentials for consciousness. It may be found spelled Hay-Aleph, Hay-Yod or simply Hay (Suares: "Life is one.").
5: Hay: Life: the response (4/Dallet) to the motion (3/Ghimel) of material (2/Bayt) moved by the spirit (1/Aleph). The first four letters (1+2+3+4=10) contain the structural seed of life; the last four letters (6+7+8+9=30) express life's potential for actualization in existence (45=Adam: the existence (10) of the interior life (5) and its movement (30) in manifestation are one in Man). This is another reason why Hay is the only singular letter: the inner life and the outer life it balances is one.
Hay/5, Life is a balance of inner and outer energies. On the one side it resists (Dallet) the uncontrolled flow of the primary energies, Aleph-Bayt-Ghimmel; on the other it propagates (Waw) itself and builds structures to explore evolutionary potentials for consciousness (Zayn-Hayt-Tayt).
The Qabala understands the centrality of life as a mediation of internal and external energies. The basic energies are fundamentally biological in nature. Their purpose is to bring life into being and the alphabet is completely structured toward that end.
Aleph, the infinite intemporal, is contained in Bayt and gives rise to the infinite uncontrolled movement (energy flow) of Ghimmel which is resisted with Dallet allowing Life to be and propagate with Waw, so it can choose (Zayn: specific probability) from a pool or banquet of possibilites (Hhayt: sum of probabilities) to build a structure (Tayt) for Existence (Yod).
See: Two Lives in the Tree of Life
Infrastructure: Hay appears in the spelling of only one letter: Phay-Hay. It contributes at the second level to the letters Aleph, Kaf, Sammekh and Qof, all letters with their roots in unstructured energy/consciousness.