"No other science is equal to that which develops in the life of the student the character of God. Those who become followers of Christ find that new motives of action are supplied, new thoughts arise, and new actions must result. But they can make advancement only through conflict; for there is an enemy who ever contends against them, presenting temptations to cause the soul to doubt and sin. There are hereditary and cultivated tendencies to evil that must be overcome. Appetite and passion must be brought under the control of the Holy Spirit. There is no end to the warfare this side of eternity. But while there are constant battles to fight, there are also precious victories to gain; and the triumph over self and sin is of more value than the mind can estimate. CT 20.2"
"For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would."
Both passages describe an internal conflict between the flesh/sinful nature and the spirit/desire to follow God. Galatians 5:17 describes the conflict between the flesh and the Spirit, while EGW describes the conflict between hereditary tendencies to evil and the control of the Holy Spirit.