Shiva Purana
वायुरुवाच्व ॥ परोक्षमपरोक्षं च द्विविधं ज्ञानमिष्यते ॥ परोक्षमस्थिरं प्राहुरपरोक्षं तु सुस्थिरम् ॥ ९८ ॥
Vāyu said:— Knowledge is of two types: indirect and direct. They say that the former is unsteady and the latter is stable.
english translation
vAyuruvAcva ॥ parokSamaparokSaM ca dvividhaM jJAnamiSyate ॥ parokSamasthiraM prAhuraparokSaM tu susthiram ॥ 98 ॥
hk transliteration by Sanscript