Brahmacārī is not he is impotent. He can marry. He can beget children. But self-restrained. He's so self-restrained, that he's not disturbed.
So one who is in the transcendental position, he's dhīra. One poet, poet Kālidāsa, he has described, dhīra means: "Even in the presence of provocation, one who is not disturbed, he's called dhīra." He has described about Lord Śiva. When Lord Śiva was being worshiped by Pārvatī, Lord Śiva was naked and Pārvatī was worshiping the śiva-liṅga, but he did not become agitated. Therefore Kālidāsa has described: dhīra. Dhīra. One who is not... The first disturbance is sexual disturbance. So anyone, although he is completely potent with all the potencies, but still, he is not disturbed with sex impulses, he's called dhīra. Actually, that is called brahmacārī. Brahmacārī is not he is impotent. He can marry. He can beget children. But self-restrained. He's so self-restrained, that he's not disturbed. Unless he desires that "I shall have sex and for begetting children," he's not disturbed. That is called dhīra. Not by seeing any woman or man, one is disturbed.