Text 35]
Calculation of Time, from the Atom
433
PURPORT
The duration of one hundred years in the life of Brahmā has already been discussed in many places in this work, and it is described in  Bhagavad-gītā  also (Bg. 8.17). Fifty years of the life of Brahmā are already over, and fifty years are yet to be completed; then, for Brahmā also, death is inevitable.
TEXT 35
पूर्वस्यादौ परार्धस्य ब्राह्मो नाम महानभूत् । कल्पो यत्रामवद्वक्षा शब्दब्रह्मेति यं विदुः ॥३५॥
pūrvasyādau parārdhasya brāhmo nāma mahān abhūt kalpo yatrābhavad brahmā śabda-brahmeti yam viduḥ
pūrvasya —of the first half;  ādau —in the beginning;  para-ardhasya —of the superior half;  brāhmaḥ —Brāhma-kalpa;  nāma —of the name;  mahān —very great;  abhūt —was manifest;  kalpaḥ —millennium;  yatra —whereupon;  abhavat —appeared;  brahmā —Lord Brahmā;  śabda-brahma iti —the sounds of the  Vedas ;  yam —which;  viduḥ —they know.
TRANSLATION
In the beginning of the first half of Brahmā's life, there was a millennium called Brāhma-kalpa wherein Lord Brahmā appeared. The birth of the Vedas was simultaneous with Brahmā's birth.
PURPORT
According to  Padma Purāṇa  ( Prabhāsa-kaṇḍa ), in thirty days of Brahmā many  kalpas  take place, such as Varāha-kalpa, Pitṛ-kalpa, etc. Thirty days make one month of Brahmā, beginning from the full moon to the disappearance of the moon. Twelve such months complete one year, and fifty years complete one  parārdha , or one half the duration of the life of Brahmā. The Śveta-Varāha appearance of the Lord is the first birthday of Brahmā. The birth date of Brahmā is in the month of March, according to Hindu astronomical calculation. This statement is reproduced from the explanation of Śrīla Viśvanātha Cakravartī Thākur.