Poetic, expert and silent. One who is too much talkative, that means he's lacking in devotion. He should simply talk about Kṛṣṇa, nothing more. And when he, when one is actually absorbed in Kṛṣṇa thought, he cannot talk nonsense. He has no time. He does not waste time.
So these are the quali . . . here, he's called sādhu. Sādhu means these are the qualification. Of course, not that we may develop all these qualities immediately, but sādhu means this. Sādhu means, what is called, pious man. These are the qualities of pious man, sādhu. And śāstra. Śāstra means the scripture. By study of scripture, you can develop these qualities. That is called scripture. That is authorized scripture.
Just like you study some book, and you develop some quality after reading that book, similarly, when you actually have scripture, then you develop all these qualities. And guru, guru, spiritual master, means who teaches you all these things.
So you have to make your progress sādhu-śāstra-guru vākya. You have to corroborate whether guru, what guru is speaking, whether it is there in the scripture; what scripture is speaking, whether that is in the character of guru, or in the sādhu, saintly person, or spiritual master. So you have to always make comparison with three things: sādhu, śāstra, guru.
Nobody can become a spiritual master who has no reference to the scriptures and these qualities. Nobody can be accepted as a qualified man, he has not . . . if one has not developed his character through the scripture under the instruction of guru.
So sādhu-śāstra-guru. A sādhu, a guru . . . here Caitanya Mahāprabhu says, sādhu-śāstra. That sādhu includes guru also, because a spiritual master, unless he's a sādhu, he cannot be a guru, cannot be a spiritual master. And the primary qualification of spiritual master: that he is completely surrendered to Kṛṣṇa, completely Kṛṣṇa conscious person. These are the things.
So Lord Caitanya said, sādhu-śāstra-kṛpāya yadi kṛṣṇonmukha haya. Now, the sādhu's qualification is he's merciful, friendly . . . so the sādhus, they take the risk of becoming friendly and merciful to the fallen conditioned souls, and they preach the message of Godhead. Therefore their mercy is required. They are merciful, by nature. By nature, they are merciful. One who is sādhu, one who is devotee, by nature he has developed that merciful quality, friendly quality. So their business is to enlighten those who are ignorant, those who are fully absorbed in this material concept of life. Therefore they preach.
And we have to take that mercy. If we don't accept . . . suppose a man is fallen in the pit and he's trying to come out, and another man drops a rope, "Please catch it. I shall take you out of the pit." He does not catch it. Then how he can be taken out? So sādhu and śāstra, they're always ready to give you mercy, but you have to take it.