Brihat Parashara Hora Shastra
अहोरात्रस्य पूर्वान्त्यलोपाद् होराऽवशिष्यते। तस्य विज्ञानमात्रेण जातकर्मफलं वदेत्॥ १॥
Importance of Hora. The word Hora is derived from Ahoratr after dropping the first and last syllables. Thus Hora (Lagnas) remains in between Ahoratr (i.e. day and night) and after knowing Hora the good and bad effects of a native be known.
english translation
ahorAtrasya pUrvAntyalopAd horA'vaziSyate। tasya vijJAnamAtreNa jAtakarmaphalaM vadet॥ 1॥
hk transliteration by Sanscript