Although men’s actions may be free (because done spontaneously and by a previous judgment of reason), they do not cease to be necessary with respect to the divine decree and foreknowledge. Now the foreknowledge of God implies indeed the infallibility of futurition and of the event and the necessity of consequence, and yet does not imply coaction or violence, nor take away from the will its intrinsic liberty. - Institutes, third topic, question 12 (p. 211, english trans.)I like it! Read Hubner's comments at the following link.
Turretin and Compatibilism: Man's Freedom and God's Decree