Now I say. — This phrase introduces a further and fuller explanation of what is involved in the state of nonage, as compared with that of adult freedom.
A child — i.e., an infant, a minor; though the term is not technically chosen.
Differeth nothing from a servant. — Both the child and the slave were incapable of any valid act in a legal sense; the guardian was as entirely the representative of the one as the master of the other. Both the child and the slave were subject to the same restraint, discipline, correction.
Though he be lord of all. — Strictly speaking, the inference from this would be that the father was dead. This, however, is a point that does not really enter into the Apostle’s thoughts. The illustration does not hold good in all particulars, but in the chief particulars — viz., the state of constraint and subordination in which the minor is placed so long as he is a minor.