Vanity joined with pride can be detected in the fact that, in seeking God, miserable men do not rise above themselves as they should, but measure him by the yardstick of their own carnal stupidity, and neglect sound investigation; thus out of curiosity they fly off into empty speculations. They do not therefore apprehend God as he offers himself, but imagine him as they have fashioned him in their own presumption. When this gulf opens, in whatever direction they move their feet, they cannot but plunge headlong into ruin. Indeed, whatever they afterward attempt by way of worship or service of God, they cannot bring as tribute to him, for they are worshipping not God but a figment and a dream of their own heart.
The Institutes of the Christian Religion (Louisville, KY; Westminster John Knox Press; 1974) Vol. 1.4.1. p. 47-48