The reason there is always a log in my eye and a splinter in yours....
When I see a fault in someone else it magnifies the same fault that lurks inside me. The splinter is a chip off the block made of the same material. Because your fault tends to magnify my fault and I don't want to see my own fault first, then I attack your fault to quiet my own discomfort.
A splinter may even be the same size in both your eye and mine. But through the principle of perspective the relative size of trying to look past a splinter that is so close to me that is in me makes it appear as big as a log. And as far as useful vision is concerned it is the size of a log.
The log is always in my eye, not just because it may or may not be bigger than the splinter in another's eye but because (1) it is composed of the same material and (2) it is at extremely close range making it appear much larger and (3) it hopelessly distorts my ability to be of any use helping the other person. The splinter in my own eye (notice it is not in my hand or anywhere else) is the only one I have an effective choice of dealing with. If I attend to my own repair, realize I need the assistance of someone who no longer has blurred and obstructed vision to help me remove my own problem, then I will experience and model to others the very process and ensuing freedom that they need to experience and enjoy. Then I can assist them in humility, compassion, patience and sympathy sharing from a new perspective of a recovering fault-victim. Instead of being a fault-finder and accuser I can now become a hope-sharer and an assistant for the Divine Surgeon.
By story-telling my own experience of transformation from victim to healed I bear testimony and thereby effectuate the growth of the Body. Testifying was the trademark activity of the early New Testament believers and it was their most effective tool.