Sentence:  ... it was worthy of extraordinary note, how that upstart family of the Kings of "Pergamus" had raised it selfe to marvellous greatnesse, in very short space, from the condition of meere slavery: whereof a principall cause was, the brotherly love maintained by them, with singular commendation of their pietie. Neither was "Philip" ignorant of these examples; but is said to have propounded the last of them, to his owne children, as a patterne for them to imitate. Certainely hee had reason so to doe: not more in regard of the benefit which his enemies reaped by their concord, than in remembrance of the tender <WSD>fosterage</WSD>, wherewith King "Antigonus" his Tutor had faithfully cherished him in his minoritie. 
Meaning of the word marked with <WSD> tags:  The act of fostering another's child as if it were one's own.