Everything was made through him; and not one thing was made without him. (John 1:3)
This verse talks more specifically about the creative action of the Logos, expressed both positively and negatively: he created everything; and, without him, nothing would have been created. This idea would have been familiar to Jews through the passage about Wisdom and her role in creation (Proverbs 8:22-31). The figure of the Logos, Jesus Christ, now fulfils this role.
In this verse, we see both the grand and cosmic nature of Christ, as well as His detailed and intimate nature. Christ was there at creation and created everything: both the grand and the cosmic. If it were not for Christ, nothing would have come into being – not one single thing. When we think of all the objects and people with whom we shall come into contact today and think none of them might have existed, that is startling. How would we have even coming into being ourselves?
Here we see the God who knows and defines the big picture: all the events of the world – even Brexit negotiations. Here we see the God who is interested in the details: every constituent part of our lives. He set it all into motion. This should humble us: as individuals, we are so small in the whole canvas of creation. Yet, it also ought to lift us up: each of us is placed so carefully and lovingly here. We are called to remember that the goodness of creation comes through Christ.
 Well, most of: there is some debate as to whether ὅ γέγονεν (“what has been made”) goes with this verse or the next verse. I think it more makes sense to take it with the next verse, as most of the early Church Fathers did. Doing so also makes this verse more balanced and poetic (although makes v.4 a bit clunkier).