I would say a "strain" is a line of thinking here. "Connected" means "coherent". He reached certain conclusions in his youth, and youthful thinking can be disjointed and lacking cohesion. But he is writing about them now, as an adult through an adult lens, and so he wonders if the way he has organized and described them *now* is more linear, logical, and coherent than the way they actually occurred to him *then* as a youth.