यदा वै श्रद्दधात्यथ मनुते नाश्रद्दधन्मनुते श्रद्दधदेव मनुते श्रद्धा त्वेव विजिज्ञासितव्येति श्रद्धां भगवो विजिज्ञास इति ॥ ७.१९.१ ॥
In plain words
"When a man has faith, then he thinks; one who has no faith does not think. Only one who has faith thinks. But one must seek to understand faith." "Sir, I seek to understand faith."
The commentators
Chāndogyopaniṣadbhāṣyam· bhāṣya
मन्तव्यविषये आदरः आस्तिक्यबुद्धिः श्रद्धा ॥
In plain words
Faith is a reverent attitude and a firm conviction toward that which is to be understood.
Close to the Sanskrit
Reverence toward the object of reflection, an intellect of belief, is faith.