Comment after something happens, not before!

epiphany.cs

public void Write(RecordBase record)
{
    if (record == null)
        throw new ArgumentNullException("record");

    // we have something to write

    var spec = Spec.GetRecordSpec(record);
    if (spec == null)
        throw new UnknownRecordTypeException("Unknown record type: " + record.GetType().FullName);

    // we know how to write it (because we have the spec)

    using (var memoryStream = new MemoryStream())
    {
        var binaryWriter = new BinaryWriter(memoryStream, _writer.Encoding);
        spec.Write(binaryWriter, record);

        // record was successfully converted to bytes

        _writer.WriteBigEndian((int) memoryStream.Length);

        // length of record written out to stream

        memoryStream.Position = 0;
        memoryStream.CopyTo(_writer.Stream);

        // record data written out to stream
    }
}