Katha-1-3-4-indriyāṇi

Sri Shankara’s Commentary (Bhashya) translated by S. Sitarama Sastri

Those who are versed in the construction of chariots call the senses, such as the eye and the rest, horses, from the similitude of their drawing the body. Know the objects (such as form, etc.), of these senses, regarded as horses, to be the roads. The intelligent call the âtman combined with the body, the senses and the mind, the enjoyer, i.e., one in Samsâra; for, the pure âtman cannot be the enjoyer. Its enjoyment is only the product of its conditions such as intelligence, etc.; accordingly also, other srutis declare that the pure âtman is certainly not the enjoyer. ‘It seems to think and to move’; only if this is so, in working out the analogy of the chariot to be described, it will be appropriate to understand. ‘The Vishnu Pâda’ as the pure âtman but not otherwise; for, there can be no going beyond Samsâra in the case of the pure âtman.

Links
Various resources on the Kathopanishad
Upanishad Series – Katopanishad Commentary by Swami Chinmayananda