CC Ādi 1.35

mantra-guru āra yata śikṣā-guru-gaṇa
tāṅhāra caraṇa āge kariye vandana
Word for word: 
mantra-guru — the initiating spiritual master; āra — and also; yata — as many (as there are); śikṣā-guru-gaṇa — all the instructing spiritual masters; tāṅhāra — of all of them; caraṇa — unto the lotus feet; āge — at first; kariye — I offer; vandana — respectful obeisances.
Translation: 
I first offer my respectful obeisances at the lotus feet of my initiating spiritual master and all my instructing spiritual masters.
Purport: 

Śrīla Jīva Gosvāmī, in his thesis Bhakti-sandarbha (202), has stated that uncontaminated devotional service is the objective of pure Vaiṣṇavas and that one has to execute such service in the association of other devotees. By associating with devotees of Lord Kṛṣṇa, one develops a sense of Kṛṣṇa consciousness and thus becomes inclined toward the loving service of the Lord. This is the process of approaching the Supreme Lord by gradual appreciation in devotional service. If one desires unalloyed devotional service, one must associate with devotees of Śrī Kṛṣṇa, for by such association only can a conditioned soul achieve a taste for transcendental love and thus revive his eternal relationship with Godhead in a specific manifestation and in terms of the specific transcendental mellow (rasa) that one has eternally inherent in him.

If one develops love for Kṛṣṇa by Kṛṣṇa conscious activities, one can know the Supreme Absolute Truth, but he who tries to understand God simply by logical arguments will not succeed, nor will he get a taste for unalloyed devotion. The secret is that one must submissively listen to those who know perfectly the science of God, and one must begin the mode of service regulated by the preceptor. A devotee already attracted by the name, form, qualities, etc., of the Supreme Lord may be directed to his specific manner of devotional service; he need not waste time in approaching the Lord through logic. The expert spiritual master knows well how to engage his disciple’s energy in the transcendental loving service of the Lord, and thus he engages a devotee in a specific devotional service according to his special tendency. A devotee must have only one initiating spiritual master because in the scriptures acceptance of more than one is always forbidden. There is no limit, however, to the number of instructing spiritual masters one may accept. Generally a spiritual master who constantly instructs a disciple in spiritual science becomes his initiating spiritual master later on.

One should always remember that a person who is reluctant to accept a spiritual master and be initiated is sure to be baffled in his endeavor to go back to Godhead. One who is not properly initiated may present himself as a great devotee, but in fact he is sure to encounter many stumbling blocks on his path of progress toward spiritual realization, with the result that he must continue his term of material existence without relief. Such a helpless person is compared to a ship without a rudder, for such a ship can never reach its destination. It is imperative, therefore, that one accept a spiritual master if he at all desires to gain the favor of the Lord. The service of the spiritual master is essential. If there is no chance to serve the spiritual master directly, a devotee should serve him by remembering his instructions. There is no difference between the spiritual master’s instructions and the spiritual master himself. In his absence, therefore, his words of direction should be the pride of the disciple. If one thinks that he is above consulting anyone else, including a spiritual master, he is at once an offender at the lotus feet of the Lord. Such an offender can never go back to Godhead. It is imperative that a serious person accept a bona fide spiritual master in terms of the śāstric injunctions. Śrī Jīva Gosvāmī advises that one not accept a spiritual master in terms of hereditary or customary social and ecclesiastical conventions. One should simply try to find a genuinely qualified spiritual master for actual advancement in spiritual understanding.