For that extra special emphasis that only Famspear deserves:
Prior to 1909:
“… We do not mean to say that an act laying by apportionment a direct tax on all real estate and personal property, or the income thereof, might not also lay excise taxes on business, privileges, employments, and vocations. But this is not such an act, …”
Keeping in mind:
LABOR.
“Labor,” “business,” and “work” are not synonyms. Labor may be business, but it is not necessarily so; and business is not always labor. Labor implies toll; exertion producing weariness; manual exertion of a toll some nature.
BLACK’S LAW DICTIONARY
This is stating that an Act could lay simultaneously both direct and indirect categories of taxation; however, for the purposes of the IRC, this is not the case. It is discussing a 'direct tax', which includes a tax on realty, personal property, and related income; again this is aside from 'capitation tax', which is not a 'direct tax'. Ergo, this is what the XVI Amendment served to do, to remove income from direction taxation and place it within indirect taxation. Capitation taxes was never a subject or concern of this.
Furthermore this substantiates exactly what [XVI Amendment] 'incomes' are, which is to say a tax upon the gains and profits deriving from realty and personal property, whatever the source of such may actually be. And that this is where the confusion had lied; that type of 'income' is not the revenue or stock generated from laboring, being only taxable by a 'capitation tax'... this serves as the basis for obtaining that which is only taxable under a 'direct tax' and subsequently the 'income tax'.