The authorized descriptions of bhakti, or devotional service, following in the footsteps of previous ācāryas, can be summarized in the following statement by Śrīla Rūpa Gosvāmī: "First-class devotional service is known by one's tendency to be fully engaged in Kṛṣṇa consciousness, serving the Lord favorably." The purport is that one may also be in Kṛṣṇa consciousness unfavorably, but that cannot be counted as pure devotional service. Pure devotional service should be free from the desire for any material benefit or for sense gratification, as these desires are cultivated through fruitive activities and philosophical speculation. Generally, people are engaged in different activities to get some material profit, while most philosophers are engaged in proposing transcendental realization through volumes of word jugglery and speculation. Pure devotional service must always be free from such fruitive activities and philosophical speculations. One has to learn Kṛṣṇa consciousness, or pure devotional service, from the authorities by spontaneous loving service.
This devotional service is a sort of cultivation. It is not simply inaction for people who like to be inactive or devote their time to silent meditation. There are many different methods for people who want this, but cultivation of Kṛṣṇa consciousness is different. The particular word used by Śrīla Rūpa Gosvāmī in this connection is anuśīlana, or cultivation by following the predecessor teachers (ācāryas). As soon as we say "cultivation," we must refer to activity. Without activity, consciousness alone cannot help us. All activities may be divided into two classes: one class may be for achieving a certain goal, and the other may be for avoiding some unfavorable circumstance. In Sanskrit, these activities are called pravṛtti and nivṛtti-positive and negative action. There are many examples of negative action. For instance, a diseased person has to be cautious and take medicine in order to avoid some unfavorable illness.
Those who are cultivating spiritual life and executing devotional service are always engaged in activity. Such activity can be performed with the body or with the mind. Thinking, feeling and willing are all activities of the mind, and when we will to do something, the activity comes to be manifest by the gross bodily senses. Thus, in our mental activities we should always try to think of Kṛṣṇa and try to plan how to please Him, following in the footsteps of the great ācāryas and the personal spiritual master. There are activities of the body, activities of the mind and activities of speech. A Kṛṣṇa conscious person engages his words in preaching the glories of the Lord. This is called kīrtana. And by his mind a Kṛṣṇa conscious person always thinks of the activities of the Lord—as He is speaking on the Battlefield of Kurukṣetra or engaging in His various pastimes in Vṛndāvana with His devotees. In this way one can always think of the activities and pastimes of the Lord. This is the mental culture of Kṛṣṇa consciousness.
Similarly, we can offer many services with our bodily activities. But all such activities must be in relationship with Kṛṣṇa. This relationship is established by connecting oneself with the bona fide spiritual master, who is the direct representative of Kṛṣṇa in disciplic succession. Therefore, the execution of Kṛṣṇa conscious activities with the body should be directed by the spiritual master and then performed with faith. The connection with the spiritual master is called initiation. From the date of initiation by the spiritual master, the connection between Kṛṣṇa and a person cultivating Kṛṣṇa consciousness is established. Without initiation by a bona fide spiritual master, the actual connection with Kṛṣṇa consciousness is never performed.
This cultivation of Kṛṣṇa consciousness is not material. The Lord has three general energies—namely the external energy, the internal energy and the marginal energy. The living entities are called marginal energy, and the material cosmic manifestation is the action of the external, or material, energy. Then there is the spiritual world, which is a manifestation of the internal energy. The living entities, who are called marginal energy, perform material activities when acting under the inferior, external energy. And when they engage in activities under the internal, spiritual energy, their activities are called Kṛṣṇa conscious. This means that those who are great souls or great devotees do not act under the spell of material energy, but act instead under the protection of the spiritual energy. Any activities done in devotional service, or in Kṛṣṇa consciousness, are directly under the control of spiritual energy. In other words, energy is a sort of strength, and this strength can be spiritualized by the mercy of both the bona fide spiritual master and Kṛṣṇa.