One thing is certain. The breast is not a sweat gland or a modified sweat gland, as should be apparent both intellectually and esthetically. Moreover, in our opinion, the breast is not an organ into itself, despite the fact that in postpubescent women it has a specific function, namely, lactation. The reason for these opinions will become apparent as a reader reads on and will be elaborated on in Part III of this series of articles. Part II will be devoted to anatomic and histologic attributes of the breast and Part III to pathologic processes of it.