Charak Samhita
विकारः प्रकृतिश्चैव द्वयं सर्वं समासतः । तद्धेतुवशगं हेतोरभावान्नानुवर्तते ॥४१॥
Everything can be categorized into being in a normal or an abnormal state. Both of these categories depend upon causes. Nothing can happen without a cause.
english translation
vikAraH prakRtizcaiva dvayaM sarvaM samAsataH । taddhetuvazagaM hetorabhAvAnnAnuvartate ॥41॥
hk transliteration by Sanscript