The ''' Epiklesis''' was a great dispute between Orthodox Church and other churches that needed to know '' how the change takes place'' and '' at what moment does it take place''.
The Orthodox Church has always held the view that it is a mysterious reality, and that it is not within the power of our minds to apprehend it. It comes by the way of prayers. Not a ''moment of consecration'' . They look upon the entire Eucharistic Prayer as forming a single and indivisible whole, so that the three main sections of the prayer, [[ Thanksgiving]], [[ Anamnesis]], and '''Epiclesis''', all form an integral part of the one act of consecration.
So, such a ''moment of consecration'' cannot come until the '' [[Amen]]'' of the Epiclesis.
Another dispute questioned if the prayer was necessary. So, at least in the Slavic tradition, the [[Prayer of the Third Hour]] was added to the '''epiklesis'''. It is a prayer asking the Lord to send the Holy Spirit to the Church right now as he did ''"at the third hour"'' to his holy [[apostles]] and [[disciples]] on [[ Pentecost]].