‘But the Comforter, the Holy Spirit, whom the Father will send in My name, He shall teach you all things and bring all things to your remembrance, whatsoever I have said unto you’ (John 14:26).
What practical meaning have these words other than that we must pray every day that the Holy Spirit be sent to us, just as we pray every day for Our daily bread?
God is willing every day to send us the Holy Spirit, but He seeks from us that we pray every day for Him to be sent to us. For as, with regard to bread, there is sometimes abundance and sometimes dearth, so it is with regard to the Holy Spirit. The Holy Spirit comes to us and leaves us according to our good works and our patience. Therefore the Church has ordained that the first morning service in church begin with the invocation of the Holy Spirit: ‘O heavenly King, O Comforter, Spirit of truth – come!’, and after that comes the prayer: ‘Give us our daily bread.’ Why? Because, without the Holy Spirit, we cannot even make use of bread in the way that we must for our salvation.
‘He shall teach you all things.’ That is: every day and every night, according in the situation in which you find yourself, He will instruct you, advise you and direct you in what you must think, say and do. Therefore, ask God only for the Holy Spirit, and He will Himself bring all that you need in any given moment. When He has descended upon you, you will know all things and be capable of all that is needful.
‘And bring all things to your remembrance, whatsoever I have said unto you’. That is: do not fear that you will forget My teaching and My words. The Holy Spirit knows all that I know; so, when He is present with you, then all My teaching will be present in you together with Him.
O Lord the Holy Spirit, be pleased to descend upon us, not according to our merit but according to the merit of the Lord Jesus, and according to Thine endless goodness. To Thee be glory and praise forever.
St Nikolai Velimiroviċ, The Prologue from Ochrid
St Vasilios Greek Orthodox Church 