Patanjali's yoga sutras

एतेन भूतेन्द्रियेषु धर्मलक्षणावस्थापरिणामा व्याख्याताः॥१३॥

3.13 etena bhūtendriyesu dharma-laksana-avasthā parināmā vyākhyātāh

etena = by this

bhūta = an object

indriyesu = in the senses

dharma = essential nature

laksana = qualities, temporal state

avasthā = thought, content of the mind

parināmah = transformation

vyākhyātāh = as explained

This explains how holding an object in the senses transforms thought into a state that reveals its essential nature.