Ch. 16, Mishnas 6: If a non-Jew comes to extinguish a fire that broke on on a Jew’s property on Shabbos, we neither encourage nor dissuade him. He should be rewarded after the fact, but we must not appoint him as our agent in doing something we ourselves are not permitted to do. With our own minor child, we stop him from putting out a fire. Note that the law since medieval times is that we put out any fire on Shabbos that has the least possibility of becoming dangerous. Mishna 7: We overturn a bowl to interpose between a candle and a beam that might catch fire (though we don’t extinguish unless it becomes dangerous), and we overturn a bowl and cover feces to prevent a child from playing with it, and a scorpion to prevent it from biting us. The gemara winds through a beautiful debate seeking to understand the limits of trapping and/or killing dangerous creatures on Shabbos. Ultimately the law is that we kill any creature that poses a definite threat to human life. Other harmful creatures may also be killed on Shabbos by “innocently treading” on them – as if we did it by mistake – so we don’t give the appearance of desecrating Shabbos in a borderline situation.