Spurgeon says this well.
I might add…
John 6:37-40 All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out. 38 For I came down from heaven, not to do mine own will, but the will of him that sent me. 39 And this is the Father’s will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day. 40 And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.
John 6:44-45 No man can come to me, except the Father which hath sent me draw him: and I will raise him up at the last day. 45 It is written in the prophets, And they shall be all taught of God. Every man therefore that hath heard, and hath learned of the Father, cometh unto me.
John 6:63-66 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life. 64 But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who should betray him. 65 And he said, Therefore said I unto you, that no man can come unto me, except it were given unto him of my Father. 66 From that time many of his disciples went back, and walked no more with him.
Rainbow Trout 