Language is an interesting field to study. Words should give 
expression to what we have in our minds and what we want to convey. 
And this is where we sometimes have trouble to bring certainty 
when we translate from one language to another.
This is the problem we are faced with in Matthew 21:42.
“42 Jesus said unto them, Did you never read in the scriptures, 
The stone which the builders rejected, the same is become the 
head of the corner: this is the Lord’s doing, and it is marvellous 
in our eyes?” King James Version.
“...The stone the builders rejected has become the capstone...” 
New International Version.
“The stone that the builders rejected
has become the cornerstone;...” English Standard Version

This is a quotation from Psalm 118:22:, which is also quoted in 
Acts 4:11.

Psalm 118:22: “The stone which the builders refused is become the 
head stone of the corner. Or Capstone...”

To what stone is Jesus referring to? A capstone or a corner stone, 
or the head of the corner? 

The Hebrew word in Psalm 118:22 should be understood as referring 
to a cornerstone from which all measurements and direction was 
taken for the erection of the whole building. But in Greek two 
different words are used when referring to a Capstone or a 
Cornerstone.

In Matthew 21:42, Mark 12:10, Luke 20:17 as well as Acts 4:11 the 
quotation from Psalm 118:22 all refer to Jesus. In all these 
quotations “kefalyn gõnias” is used, meaning “head of the corner”. 

In Ephesians 2:20 Paul uses “akrogõnaios” meaning a capstone. In 
the next verse Paul says that in Christ the the whole building is 
“joined together” and rises to become a holy temple in the Lord. 
This would then refer to a “capstone”.

Peter uses “akrogõnaios” (capstone) in 1 Peter 2:4 - 7 where he 
points out that God had chosen Jesus to be the “living stone”. 
In most translations this word is not translated as “capstone”, 
but as “cornerstone”. Yet in the next verse Peter uses the word 
“kefalyn gõnias” meaning the “head of the corner”, which would 
refer to a “cornerstone”. Peter uses two different words in the 
same paragraph.
Let us look at the translation found in the English Standard 
Version: “As you come to him, a living stone rejected by men but 
in the sight of God chosen and precious, you yourselves like 
living stones are being built up as a spiritual house, to be a 
holy priesthood, to offer spiritual sacrifices acceptable to God 
through Jesus Christ. For it stands in Scripture: 
'Behold, I am laying in Zion a stone,
a cornerstone chosen and precious,
and whoever believes in him will not be put to shame.'
So the honour is for you who believe, but for those who do not 
believe,
'The stone that the builders rejected
has become the cornerstone,'”
The translators do not make any difference between these two 
different words Peter uses, and translate both with “cornerstone”. 
Yet it seems as though Peter was referring to two different stones!

Let us then consider whether there were indeed different stones 
used in buildings at that time. What was a capstone and what a 
cornerstone?

A Capstone. 
When an arch was built, whether as part of a building or as a 
stone bridge, a specific wedge stone was hewn slanting on both 
sides. This stone had the function to join together both sides 
of the arch, to become a unity. This stone as the central point 
of focus, was often decorated to honour some deity or important 
person. Without this stone, the two parts of the arch would tumble 
in. Both Paul and Peter say that Jesus is indeed this “capstone”.

A Cornerstone.
When a building was to be erected, a specific large stone was 
hewn to perfect measures and carefully put on the corner of the 
building as part of the foundation. All measures and direction 
was then taken from this stone to ensure that the building is 
built square and to the correct measures.
In modern times this original purpose of a cornerstone is no longer used, 
but the word usually refers to a large stone near the base of a building 
where two walls meet, often giving information about the building and 
sometimes put in position with a ceremony. 

Yet Matthew uses another word, “lithon” (stone) in verse 21:44 to refer to 
Jesus. 
There he indicates Jesus as the stone that could refer to either a 
”capstone” or a “cornerstone”.
“And the one who falls on this stone will be broken to pieces; 
and when it falls on anyone, it will crush him.” One can fall 
on a cornerstone, but it is a capstone that can fall on someone, 
crushing him.

Jesus is the cornerstone from whom we should take all our measures 
and direction. But He also is the capstone that joins together what 
needs to be together.

Since it is uncertain to which of the two stones Matthew is 
referring in verse 42, a definite choice is not obvious. Versions 
using either of the two words are putting the emphasis on one of 
the important meanings this verse brings to our attention. 
But a final decision is not possible.

God bless,
Herman.

You are welcome to comment at the bottom of this page, or directly 
to me at bibledifferences@gmail.com.