The DR number, Diederich Rank, refers to the highest number in Diederich's frequency listing, which you can see here: Diederich Ranking.
DR 160. Vivamus atque amemus. ~ Note: The words are adapted from one of the poems of Catullus, 5: Vivamus, mea Lesbia, atque amemus.
DR 161. Mens videt, mens audit. ~ Note: This is one of the sayings Erasmus included in his Adagia, 4.5.12.
DR 161. Mens cuiusque is est quisque. ~ Note: This is the motto of the Pepys family and, as such, it is inscribed on the Pepys Library.
DR 162. A magnis, maxima. ~ Note: This expresses the idea that from big things come the biggest things, the greatest outcomes, the largest effects, etc.
DR 163. Ne ignem ad ignem. ~ Note: The "ne" lets you know that you are dealing with a negative command, even without the verb: don't (add) fire to fire.
DR 163. Terra corpus est, at mens ignis. ~ Note: The words go back to the archaic Roman poet, Ennius.
DR 165. Male creditis hosti. ~ Note: You can find this observation of the danger of trusting one's enemies in Ovid's Fasti, 2: Quo ruitis, generosa domus? Male creditis hosti: / simplex nobilitas, perfida tela cave.
DR 166. Tene fortiter! ~ Note: Fortiter is the adverbial form of the adjective fortis.
DR 166. Ferte fortiter! ~ Note: With this one, it is possible to capture a bit of the Latin word play in English, too: "Bear up bravely!" (Ferte is the second-person imperative: fer, singular; ferte, plural.)
DR 166. Forti animo esto. ~ Note: The phrase "forti animo" is in the ablative and is being used descriptively in the predicative with the future imperative esto; we might say in English "Be brave in spirit!" or "Have a brave heart!"