Sastra means Science, systematized knowledge of Nature. Not only physical sciences, Sastra includes spiritual sciences as well, as Indian Philosophy deals with both Matter and Spirit, Purusha & Prakriti.
Siddhanta Sastra means the Science of Astronomy & Hora Sastra means the Science of Astrology.
P N Oak was right when he said that the English word Hour is a malpronunciation of the Sanskrit word Hora. Hora Sastra means the Science of Hour, Time.
When I met the astro scholar, Avanoor Asan, he was ecstatic when he described the Master, Varaha. Said the Master was an Avatar, who came to redeem this infinite Ocean of Knowledge which is the Science of Time, this Hora Sastra , Hora Sastra Maharnava pratharane.
Aditya Dasathanayastava apta Bodha
Kapishtalo Savithru Labda vara prasada
Avantiko Muni manany avalokya Samyak
Horaam Varaha Mihiram ruchiram chakara
Savithru Labda vara prasada refers to Revealations received by the Master in higher states of Consciousness, symbolically depicted as boons from the Sun !
An astronomer, mathematician and astrologer par excellence, Varaha strode the scene like an intellectual colossus, contributing to all the three branches of the triune Astro Physics, the Thriskanda Jyotis Sastra – Siddanta, Samhita & Hora.
See how he describes The Significations of the Twelve Houses in just two lines
Kalya Swa Vikrama Griha Prathibha Kshatani
Chittotha Randhra Guru Mana Bhava Vyayani.
The Quintessence of BHS are these two verses
Planetary states are seven,
Exalted is Sampoorna,
Devoid of strength positional is Riktha
In inimical, Is Anishta Phalada called !
Fallen from Exaltation is Avarohee
Madhya in houses of fiends,
Arohinee when rising,
And Adhama in houses inimical !
Samyak balina swa tunga bhage
Sampoorna balavarjitasya Riktha
Neechamsa gathasya satrubhage
Jneya Anishtaphala Dasa prasoothu
Bhrishtasya tungath Avarohi samjna
Madhya bhaveth sa Suhrud Ucchabhamse
Arohinee nimna parichyutasya
Neecharibhageth Adhama bhaveth Sa !
BHS is Varaha’s magnum opus. wherein he spells out the principles of the Science of Time, in 384 verses of golden Sanskrit Poetry.
BHS has a great competitor, BPHS, Brihat Parasara Hora Sastra, consisting of 4000 verses.