Conjunction
not but
(now rare, archaic) Introducing a subordinate clause, frequently with that: "it is not that (the following clause) is not the case". [17th–19th c.]
I see my way as birds their trackless way. I shall arrive, what time, what circuit first, I ask not but unless God send his hail Or blinding fire-balls, sleet or stifling snow, In some time, his good time, I shall arrive He guides me and the bird. In his good time. Robert Browning
Silence - Speak not but what may benefit others or yourself; avoid trifling conversation. Benjamin Franklin
Doubt not but angling will prove to be so pleasant that it will prove to be, like virtue, a reward to itself. Izaak Walton
I was myself the compass of that sea: I was the world in which I walked, and what I saw Or heard or felt came not but from myself; And there I found myself more truly and more strange. Wallace Stevens
The friendships of the world are oft Confederacies in vice, or leagues of pleasure; Ours has severest virtue for its basis, And such a friendship ends not but with life. Joseph Addison
I doubt not but the fire illuminating heaven on Michelmas eve was seen there – such as I never saw for the time more fearful. God sendeth us such signs but for our erudition. William Cecil, 1st Baron Burghley