One who is meditating, dhyānāvasthita-tad-gatena manasā, mind is so trained up that mind cannot think of anything else except God, that is perfection of yoga. Mind . . . we, our mind cannot be vacant. We must think of something in the mind. Not for a second we can make our mind vacant. That is not possible. So this vacancy, this mind's business—thinking, feeling and willing—when all of them are engaged in the Supreme Personality of Godhead, that is called perfect yoga system, or the topmost yoga system.
Unfortunately, the impersonalist, they have no idea of the form, form of the Lord. Because they're impersonalist, they do not accept any form of the Lord. But there is the form of the Lord. Form of the Lord there must be. God is accepted as the supreme father. In Christianity also it is accepted, the supreme father. In every religion He's accepted the supreme person, supreme father, supreme master. So how He can be imperson? From logical point of view . . . just like you are a person, your father is a person, his father is also a person, his father is also a person. Go on, even you do not know your the topmost forefather, you know it that he was a person. Similarly, the supreme father, the father of all fathers, how He can be imperson? Logically you cannot conclude. He must be a person. And that is the Vedic version also.