Since Gītopaniṣad is largely based on the principles of the Upaniṣads, it is not surprising to also find this passage in the Kaṭha Upaniṣad.

Some people who are inclined to hear about the soul may be attending lectures, in good association, but sometimes, owing to ignorance, they are misguided by acceptance of the Supersoul and the atomic soul as one without distinction of magnitude. It is very difficult to find a man who perfectly understands the position of the soul, the Supersoul, the atomic soul, their respective functions, relationships and all other major and minor details. And it is still more difficult to find a man who has actually derived full benefit from knowledge of the soul, and who is able to describe the position of the soul in different aspects. But if, somehow or other, one is able to understand the subject matter of the soul, then one's life is successful. The easiest process for understanding the subject matter of self, however, is to accept the statements of the Bhagavad-gītā spoken by the greatest authority, Lord Kṛṣṇa, without being deviated by other theories. But it also requires a great deal of penance and sacrifice, either in this life or in the previous ones, before one is able to accept Kṛṣṇa as the Supreme Personality of Godhead. Kṛṣṇa can, however, be known as such by the causeless mercy of the pure devotee and by no other way.