Baumgarten intends to establish a new philosophy through his aesthetics. The beauty he explains in Aesthetica is the central element of that philosophy. For him, the beauty is the cognition that allows us to recognize the uniqueness of a certain object which is not revealed by the so-called logical thinking, when the sensitive presentations are well expressed through appropriate ways(speech, writing, gesture, etc.) This implies that the alteration of epistemology and truth of the rationalism around the 18th century is unavoidable. Because the people who hold rationalistic views at that time do not think that the beauty can enlarge our cognition and reveal any aspect of an object which can not be uncovered by the logical thinking.
By the way, Baumgarten urges that the subject of cognition has to meet a couple of qualifications in order to experience the beauty. He explains them through some characteristics of felix aestheticus(felicitous aesthetician). The aesthetician is to be qualified for some sensitive talents such as imagination, prediction power, poetic ability, and at the same time has to make them be exercised well. He must have will for doing that for himself, argues Baumgarten, and also study an elaborated theory of art. Just then, he can enlarge his knowledge through the clear and confused cognition and come to the state of complete cognition.
It is very interesting that this aesthetician is not a person who only seeks for sensation, neglecting reason. He rather fulfills sensory cognition, being aware of the peculiar roles of reason and sensation respectively and making each of them perform its role. Though the role of reason(the so-called abstract thinking) and the one of sensation(the so-called concrete thinking) are contradict each other, the aesthetician who Baumgarten suggests as an actual person tries to hold the balance in the antagonistic tension in which the reason and sensation can fully achieve their roles and the one is never unilaterally governed by the other. In this sense, for Baumgarten, the person who longs for the beautiful thinking pursues a peculiar balanced life, namely a sort of well-rounded one. In short, there is an element of the well-rounded person in the background of Baumgarten’s aesthetics.