To control the mind is certainly the crux of all yoga systems, including the system of bhakti-yoga or K???a consciousness which is the only practical yoga system in the present age. Indeed the Bhagavad-gita states that one who has controlled the mind has already reached the Supersoul, and that the controlled and uncontrolled mind are, respectively, the best friend and the worst enemy of the conditioned soul. Vai??ava Ke? is a Bengali poem written by His Divine Grace Sri Srimad Bhaktisiddhanta Sarasvati ?hakura. This poem contains revelations and practical guidance to aid the aspiring devotee in dealing with the types of nonsense deviations which may continue to be proposed by the mind to distract a devotee until he reaches the level of pure devotional service.
The devotees and friends of ISKCON became aware of the value of these practical instructions in Vai??ava Ke? (What Kind of Devotee Are You?) when translations and commentaries on ten of its verses by His Holiness Jayapataka Swami were published in serial form in the (now defunct) periodical, ISKCON World Review. From that time, many devotees, including the publishers of this present volume, have desired that Vai??ava Ke?, together with its translation and commentary, be published in the form of a complete book so that its lessons could be repeatedly studied and reflected upon. One GBC member recently remarked that its publication was ?long overdue.?
Therefore, it is the humble desire of the publisher to present this book for the pleasure of our predecessor acaryas. It is especially dedicated to our spiritual master, His Divine Grace A. C. Bhaktivedanta Swami Prabhupada, the Founder-Acarya of the International Society for Krishna Consciousness who frequently quoted from the verses of Vai??ava Ke? in his lectures and books, and to His Divine Grace Srila Bhaktisiddhanta Sarasvati ?hakura Prabhupada, the author, as well as the Vai??avas all over the world.
This book is most pertinent and relevant for those who are trying to advance in K???a consciousness at the present moment. We must frankly admit that our own ?wicked minds? may have from time to time proposed just the kind of deviations mentioned in Vai??ava Ke? Many devotees have left full-time preaching and service in the K???a consciousness movement for precisely the types of reasons and rationalizations offered by the mind which are described in this book. Srila Bhaktisiddhanta Sarasvati ?hakur has very kindly and plainly described all these subtle matters in great detail. He has also given pragmatic advice as to how the aspiring devotee may remain absorbed in the sa?kirtana movement of Sri Caitanya Mahaprabhu without becoming yet another casualty to the attacks of the ?wicked mind? which many mistake to be their actual self as opposed to what is instead their real nature; the eternal spirit soul.
It may also be noted that in presenting his strong challenge to the mind, du??a mana! tumi kisera vai??ava?, which Srila Prabhupada has translated as ?My Dear Mind, what kind of devotee are you??, Srila Bhaktisiddhanta Sarasvati ?hakura refers to a Vai??ava or devotee according to his definition, ?who is situated in his constitutional position,? i.e. in unalloyed devotional service to the Supreme Personality of Godhead, Lord K???a. His intention is that we may not allow our minds to imagine that we are on a very elevated platform in devotional service while at the same time performing activities which are seriously detrimental to our own spiritual advancement and the advancement of the united preaching mission of Sri Caitanya Mahaprabhu. 
His Holiness Jayapataka Swami Maharaja has nicely translated the text and given an illuminating commentary based on his realizations and practical experience as a dedicated preacher in the K???a Consciousness movement all over the world for the past twenty years. The commentary is supported with extensive quotes from the books of His Divine Grace A. C. Bhaktivedanta Swami Prabhupada.