<p>4:12 <i>For the word of God is living and active, sharper than any two-edged sword, and pierces even to the dividing apart of soul and spirit, of joints and marrow, and is quick to discern the thoughts and intents of the heart</i>- The motivation for the receding appeals is that the word of God, as a title for the Lord Jesus, is right now &quot;quick to discern the thoughts and intents of our hearts&quot; in mediating for us. Such language is appropriate to a person, Jesus as the word of God, rather than to the book called the Bible. And Hebrews began by saying that as God had spoken through the words of the prophets, so He now speaks to us in His Son. But this is how He was in His mortal life here- for then He was &quot;of quick understanding&quot; too (Is. 11:3). He would have had a way of seeing through to the essence of a person or situation with awesome speed- and this must have made human life very irritating for Him at times. But who He was then is who He is now. It's the same Jesus who intercedes for us in sensitivity and compassion. See on Heb. 4:15. The reference to the sharp knife dividing up the inner parts of the body is an allusion to the priest preparing the sacrifices, and :14-16 develops this theme in relation to the Lord Jesus as our priest. Our innermost parts are laid bare and placed on the altar before God. And it is the state of the heart which is, for this priest, the most significant part of the offering. Hence the earlier appeals not to harden our hearts but to be completely confident in our hearts that in this &quot;today&quot;, at this moment, we shall be saved.</p>