"Many children, for want of words of encouragement and a little assistance in their efforts, become disheartened and change from one thing to another. And they carry this sad defect with them in mature life. They fail to make a success of anything they engage in, for they have not been taught to persevere under discouraging circumstances. Thus the entire lifetime of many proves a failure, because they did not have correct discipline when young. The education received in childhood and youth affects their entire business career in mature life, and their religious experience bears a corresponding stamp. 3T 148.1"
"Train up a child in the way he should go: and when he is old, he will not depart from it."
This is a clear and direct application of Proverbs 22:6. EGW elaborates on the long-term impact of early training, directly echoing the proverb's sentiment.
"have educated themselves in vice, and their consciences are seared. 3T 148.2"
"Speaking lies in hypocrisy; having their conscience seared with a hot iron;"
EGW uses the exact phrase 'consciences are seared,' which is a direct allusion to 1 Timothy 4:2. The context is similar, referring to a hardening of conscience due to sin.