As the deity associated with the sun’s glow or sun light, opposed to that of
the astral body, Miϑra is the god of the liminal time, viz. the points of
contact between day and night (that is, sunrise and sunset) and metonymically
between summer and winter (that is, the equinoxes). Besides the well-known
transformation of the Avestan liturgical calendar caused by the adoption of
the Egyptian solar calendar, scholars have in recent years drawn attention to
a further transformation in the liturgical calendar (for the first time H.
Humbach in 2010): the expansion of the ritual divisions of the day from three
to five. Later, J. Kellens pointed out the important role of Miϑra in
introducing the division of the day starting with sunrise. In this paper, I
will argue that Miϑra is not only associated with sunrise, but also with
sunset, introducing Miϑra as the protagonist in the process that eventually
led to the transformation of the ritual parts of the day. Moreover, I will
show that the adoption of the solar calendar caused the transformation. Both
processes are linked through a series of analogies between the day and the
year around the axis defined by Miϑra: sunrise and sunset on the one hand and
the two equinoxes on the other. I will also discuss Miϑra’s connection with
both equinoxes. The autumn equinox is celebrated at the festival of Mihragān
and corresponds to the Avestan festival paitiš.hahaiia-. With the vernal
equinox begins the new ritual year with a series of celebrations that extend
over the first week of the year. These celebrations are dedicated to the
Aməṣ̌a Spəṇta, and in them the liturgical season of each asńiia- ratu- is
introduced at a different day, thus connecting parts of the day with the
conception of the year and even hemeronyms of the first week. In this context,
I will also show that the standard Yasna, the Yasna with the dedicatory of Nōg
Nāwar, in which Miϑra takes a prominent position, is originally the Yasna for
the celebration of the opening of the new ritual year at the first sunrise
after the vernal equinox. Other important actors of the reform are the Waters
and the Frauuaṣ̌is in whose honour the other great seasonal festivals are
celebrated and to which the longest Yašts are dedicated. Most likely, the
reform of the liturgical calendar took place in Western Iran in Achaemenid
times, perhaps concurrently with other significant changes such as the
introduction of a permanent fire et
