In plain words
He is the learned one and the great man; he has won the highest good. To say it plainly, he is the one who, by firm effort, makes the mind stand still, though it rushes and whirls like the wind.
Word for word
The learned and great person, the one who has attained the highest reality, is precisely the one by whom the mind, like a fiercely moving wind, is firmly made to remain unmoving.