A Voice from the Past - Clement of Alexandria

It therefore follows, that every one of those who undertakes to promote the good of their neighbours, ought to consider whether he has betaken himself to teaching rashly and out of rivalry to any; if his communication of the word is out of vainglory; if the only reward he reaps is the salvation of those who hear, and if he speaks not in order to win favour: if so, he who speaks by writings escapes the reproach of mercenary motives

Clement of Alexandria, 150-215 AD, The Stromata or Miscellanies, Book 1, Chapter 1, (translated by Rev. Alexander Roberts and James Donaldson, Fathers of the Second Century, Philip Schaff, Christian Classics Ethereal Library, 2004, p. 424)

What are the right motives for preaching and teaching God's Word? How do we avoid the wrong ones?