This is the perfection of yoga. It is not you have to purchase one machine, or television set. It is there, and God is also there. You can see, you can hear, you can talk, provided you have got the machine. You repair it, that's all. The repairing process is Kṛṣṇa consciousness. Otherwise, everything is supplied, complete, complete set of machine you have got within you.
And just like for repairing, an expert mechanic required, similarly, you require the help of someone expert. Then you'll see that your machine is working. It is not difficult to understand. Nobody can say that it is not possible. In the śāstra we hear also. Sādhu śāstra, guru vākya, tinete kariya aikya.
Spiritual realization can be perfected by three parallel process. Sādhu. Sādhu means saintly persons, who are realized souls, sādhu. And śāstra. Śāstra means scriptures, authoritative scriptures, Vedic scriptures, śāstra. Sādhu, śāstra and guru, a spiritual master. Three parallel line.
And if you place your car or vehicle on these three parallel line, your car will go direct to Kṛṣṇa. Tinete kariyā aikya. Just like in the railway line you see two parallel lines. If they are in order, the railway carriages are carried very smoothly to the destination. Here also, there are three parallel lines—sādhu, śāstra, guru: saintly person, association of saintly person, acceptance of bona fide spiritual master, and faith in the scriptures. That's all. Then your carriage will be going nicely, without any disturbance. Sādhu śāstra guru vākya, cittete kariyā aikya (Prema-bhakti-candrikā).
So here in the Bhagavad-gītā, the Supreme Personality of Godhead explaining Himself, Kṛṣṇa. So if you say, "How can I believe that Kṛṣṇa said? Somebody has written in the name of Kṛṣṇa that 'Kṛṣṇa said,' 'God said.' " No. This is called disciplic succession. You will see in this book, Bhagavad-gītā, Kṛṣṇa, what Kṛṣṇa said, and how Arjuna understood.