The sentence is from Gellius, Attic Nights, Book 1. The historical figure Chilo, nearing death, tells his friend of an action of his that still bothers him: was it right or wrong? On a three panel panel considering capital punishment for a friend, Chilo had decided to vote guilty himself secretly but to persuade the other two jurymen to vote innocent. He had preserved his devotion to the letter of the law by voting guilty, but had saved his friend by persuading the other two to vote innocent.
ipse tacitus ad condemnandum sententiam tuli, is qui simul iudicabant, ut absolverent, persuasi.
Translation: I myself (ipse) voted guilty, but I persuaded the ones who also were judging, that they should vote not-guilty.
Somehow I have not got used to ipse . . . is having as antecedent a first-person pronoun, here the understood first-person subject of tuli . . . persuasi. I had to look at the translation to apprehend this pronoun usage.
Thanks for the reply Hylander. I had formed an incorrect understanding of ipse. This is a weakness of self-teaching; one lacks the teacher’s corrections in class. One aspect of learning is forming generalizations and rules,some of them wrong, and then revising them after some kind of correction. Many observers have noticed that autodidacts may make strange errors.
Your translation is correct, but just to be extra clear: īs in this sentence is equal to eīs - i.e., dative plural of is, ea, id. It has no connection to the first person subject of the sentence. It’s the dative object of persuāsī, and is in turn modified by quī: “I persuaded those (īs) who (quī) were also judging to vote innocent.”