How we cite our quotes: (Line)
Quote #1
The Bat that flits at close of eve
Has left the brain that won't believe.
The Owl that calls upon the Night
Speaks the Unbeliever's fright. (25-26)
Blake uses a bat and an owl as symbols for the minds and thoughts of unbelievers because they're nocturnal creatures. They're stuck in the darkness of the material world and don't have access to the light of the spirit or of imagination.
Quote #2
A truth that's told with bad intent
Beats all the Lies you can invent. (53-54)
It's worse to use a truth for false purposes than it is to just tell a lie. Not only does it cause harm, it corrupts the truth in the process. On the other hand, you might tell a lie for a basically positive reason.
Quote #3
He who replies to words of Doubt
Doth put the Light of Knowledge out. (95-96)
For Blake, there's no point in arguing with someone who's a professional doubter, since they don't really want to be convinced. You'll just end up doubting your own convictions if you fall into this kind of argument.