Christian faith has appeared to many an easy thing; nay, not a few even reckon it among the social virtues, as it were; and this they do because they have not made proof of it experimentally, and have never tasted of what efficacy it is. For it is not possible for any man to write well about it, or to understand well what is rightly written, who has not at some time tasted of its spirit, under the pressure of tribulation; while he who has tasted of it, even to a very small extent, can never write, speak, think, or hear about it sufficiently. For it is a living fountain, springing up into eternal life, as Christ calls it in John iv.