Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood. ~Acts 20:28
“There is nothing more moving in the records of human suffering and patience than the story of Paul’s Ephesian experiences as he summoned the elders of the church upon the shores of Miletus in his parting address to them.” 
Acts 20:17-38 is indeed a very moving account of Paul’s farewell address to the elders of the church at Ephesus. Over the course of Paul’s three year ministry among them, their hearts had become knit together with his. Now, as Paul meets with them on his way to Jerusalem, he gives them these admonitions, believing he could possibly be seeing them for the last time.
In addressing these elders, he instructs them of their duties. First among them is to pay attention to their own personal walk with God. “Take heed therefore unto yourselves…,” he says in verse 28. Paul also wrote to Timothy, pastor of the church at Ephesus, “Take heed unto thyself, and unto the doctrine; continue in them: for in doing this thou shalt both save thyself, and them that hear thee.  So elders are to watch over their own souls.
Their next responsibility is to watch over and feed God’s flock. “…[A]nd to all the flock, over the which the Holy Ghost hath made you overseers,  to feed the church of God, which he hath purchased with his own blood,” the verse continues. Take heed is a verb that means to pay attention to, or to apply one’s self to. They were to pay attention to not only themselves, but also the church of God. How do they take heed to the flock? By feeding it. Feed here actually means to tend a flock, to be like a shepherd; to do everything a shepherd does, like ruling and governing, nourishing, cherishing, and supplying everything the sheep need. 
The epitome of a shepherd is none other than the Lord Jesus Himself, the Good Shepherd. In John 10 the behavior of a good shepherd is contrasted with that of a hireling, who has no interest in his duty and is unfaithful in discharging it. A good shepherd, on the other hand, will lay down his life for his sheep, if necessary, to protect them from wolves. Jesus says that the hireling will flee at the sight of danger because the sheep aren’t his and he cares nothing for them, while the good shepherd cares for his own. The wolves here – and in Acts 20 – represent false teachers, or anyone whose goal it is to slaughter the sheep. So a true shepherd will protect his sheep from those who want to devour them. Jesus is that Good Shepherd Who laid down His life for us, His sheep.