The premise which seems to cause the most difficulty among interpreters of the fourth way is that the greatest in a genus is the cause of all else in the genus. This premise does not seem to be universally true, and indeed, Aquinas himself thinks that this premise is not always true, but only under certain circumstances: namely, when 1) the lesser things in the genus need a cause, and 2) there is nothing outside the genus which can be the cause. When these two conditions are met, the premise that the greatest in the genus is the cause of all else in that genus holds, since nothing gives what it does not have. Since Aquinas is dealing specifically with transcendentals like being and goodness, and since there is nothing outside the transcendentals, it follows that there is nothing outside the genus which could be a cause (condition 2). Moreover, if something has less than the maximum being or goodness or truth, then it must not have being or goodness or truth in itself. For example, how could what has circularity itself be less than fully circular? Therefore, whatever has less than the maximum being or goodness or truth must need a cause of their being and goodness and truth (condition 1).