To (correct someone) — there is nothing simpler; but to do it in such a way that it bears fruit is difficult in the extreme.  Everything must breathe with the most sincere and zealous love — not only the content of what you say, but even your glance, and expression, and tone of voice.  Then it may be hoped that this will achieve its aim.  But without this love, it is better not to undertake such a step:  it will come out worse, produce the most sorrowful discord.

St. Theophan the Recluse

For those of us who assess/correct daily, this is such wise and important advice.