The first reading today takes us to the dedication of the Temple in Jerusalem. King Solomon is there in all his legendary glory, and his prayer is that God will accept the Temple as his dwelling. The answer comes in the form of a dark cloud (or dark smoke) that fills the Temple to such an extent that the priests themselves cannot stay at their posts.
That dark cloud of God's presence was nothing new to the Chosen People. A pillar of cloud had protected them in the first stage of the Exodus, coming between them and the Egyptian army as both groups approached the Red Sea. The cloud by day (and a fire by night) led them step by step through the desert. God was their Good Shepherd, guiding them along the way.
The cloud also shows up in the New Testament, of course. Mary is told that the "power of the Most High" will "cover you with its shadow," making Mary the new dwelling-place of God on earth. When her son climbed the Mount of the Transfiguration, a "bright cloud" came upon him and the voice of the Father could be heard.
In the Catholic spiritual tradition, the cloud has another role: it becomes the cloud of "unknowing" or a "dark night" in which God's presence is so near and powerful it overwhelms all of our senses: not just our five physical senses, but the more mysterious spiritual "sense" we depend on for our bearings in relationships or in life generally; the way we perceive our place in the world and its structures. Even the saints found it disconcerting when the dark cloud of God's presence filled their little temple. What a consolation even in the darkness to hold on to the experience of Solomon and be assured that this thick darkness is really a sign of God's trustworthy nearness!