Then we shall see if my arguments come from my lips or my heart.

From Montaigne’s Essays 1.19 – That We Should Not Be Deemed Happy Until After Our Death

So it seems likely to me that [Solon] was … intending to tell us that happiness in life (depending as it does on the tranquillity and contentment of a spirit well-born and on the resolution and assurance of an ordered soul) may never be attributed to any man until we have seen him act out the last scene in his play, which is indubitably the hardest.10 In all the rest he can wear an actor’s mask: those fine philosophical arguments may be only a pose, or whatever else befalls us may not assay us to the quick, allowing us to keep our countenance serene. But in that last scene played between death and ourself there is no more feigning; we must speak straightforward French; we must show whatever is good and clean in the bottom of the pot:

Nam veræ voces tum demum pectore ab into
Ejiciuntur, et eripitur persona, manet res
[Only then are true words uttered from deep in our breast. The mask is ripped off: reality remains.]

That is why all the other actions in our life must be tried on the touchstone of this final deed. It is the Master-day, the day which judges all the others; it is (says one of the Ancients) the day which must judge all my years now past. The assay of the fruits of my studies is postponed unto death. Then we shall see if my arguments come from my lips or my heart.

je trouve vray-semblable qu’il aye regardé plus avant, et voulu dire que ce mesme bon-heur de nostre vie, qui dépend de la tranquillité et contentement d’un esprit bien né, et de la resolution et asseurance d’un’ame reglée, ne se doive jamais attribuer à l’homme, qu’on ne luy aye veu jouer le dernier acte de sa comedie, et sans doute le plus difficile. En tout le reste il y peut avoir du masque: ou ces beaux discours de la Philosophie ne sont en nous que par contenance; ou les accidens, ne nous essayant pas jusques au vif, nous donnent loysir de maintenir tousjours nostre visage rassis. Mais à ce dernier rolle de la mort et de nous, il n’y a plus que faindre, il faut parler François, il faut montrer ce qu’il y a de bon et de net dans le fond du pot,

Nam verae voces tum demum pectore ab imo
Ejiciuntur, et eripitur persona, manet res.

Voylà pourquoy se doivent à ce dernier traict toucher et esprouver toutes les autres actions de nostre vie. C’est le maistre jour, c’est le jour juge de tous les autres: c’est le jour, dict un ancien, qui doit juger de toutes mes années passées. Je remets à la mort l’essay du fruict de mes estudes. Nous verrons là si mes discours me partent de la bouche, ou du coeur

The two lines are Lucretius, III, 57.