When all of the window dressing is removed, we discover that the entire issue about when to begin the year rests with the instructions regarding the Khag of Ingathering and its tequphath (season of the year).
The late Jews tell of four תקופת (tequphath) of the year (spring, summer, autumn, and winter), each calculated as a period following one of the days of a תקופה (tequphah): the vernal equinox, the summer solstice, autumnal equinox, and winter solstice.1
It is also important for us not to confuse the occurrence of a tequphah (i.e., equinox or solstice) with the season (tequphath) although the same word is sometimes used in common speech for both.
To begin with, a tequphah (equinox or solstice), as spoken of by Scriptures, is a solar event, marking a point of passage of the earth around the sun. It represents a day wherein one of two visual effects occur.
1. A solstice day is a day when the sun, as seen along the earth’s horizon, reaches its furthest point of rising or setting either on the north or south.
2. On the day of an equinox, on the other hand, the rising and setting of the sun lies on the horizon precisely in the middle between the two solstice points. As a consequence, the length of the periods of daytime and nighttime on that day of the equinox are almost exactly equivalent.
The Hebrew word תקופת (tequphath)—various transliterated as tekufath, tequfoth, tequfath, and so forth—is a form of the term תקופה (tequphah)—tekufah, tequfah, and so forth. Tequphah is itself derived from the word קופ (quph), meaning to, “go round.”2 The term תקופה (tequphah) more precisely means, “a revolution, i.e. (of the sun) course, (of time) lapse:—circuit, come about, end”;3 a “circuit,”4 “orbit of the sun . . . circle of the year.”5