Still this book is not the first by Einhorn. He has published two similar works earlier: in 1636. - "Reformatio gentis Letticae..." (the title again is rather lengthy), being a practical manual for the local pastors encountering superstition of the locals, while "Wiederlegunge der Abgötterey..." published in 1627 is a theoretical work nailing down any manifestations of superstition.
The birth date of Paul Einhorn is not known. he was born in Iecava (to the south from Riga), he died in 1655 in Jelgava (Mittau), while preaching. Since 1636 the superintendent of Kurzeme, a priest since 1621. He is described as an ardent lutheran, why he spent so much effort fighting against superstition, but he had received a good classical education which is also seen in his works. Ironically enough, his work has gained its importance because of the description of what he tried to exterminate.
In later works Einhorn's description of the Latvian folksongs is frequently quoted, namely calling them Hymni Deorum, i.e. "hymns to gods". But he has also described some Latvian deities, mainly the mothers (Mate) - female patronesses of some specific activities or places. The list is as follows:
According to Einhorn, those who perform a particular task or activity address the corresponding Mother (like fisherman appealing to the Mother of the Sea, etc.) In his previous works he mentioned Mara as a confusion of a Latvian deity of cattle with the Holy Virgin; Historia Lettica has no mention of this deity, but it lists the deity of women Laima, equal to Fortuna or 'deity of luck', and Dekla, inferior to her, with her task being just rocking the cradle and watching over the newly-born babies.
Describing Latvian festivals, customs and names of months, Einhorn mentions in the first place the feeding of souls and Dieva dienas (Days of God), that are the same period as month of Veli or Zemlika. In this case the spelling itself is worthy of consideration. Einhorn writes Wälla-Mänes', thus leaving much space for speculation whether velis - 'the soul of a dead' and velns - 'the deity of the dead or the devil' have been already differentiated or not (the differentiation of the two is quite a problem in the later descriptions by Lange and Stender).
Einhorn provides no comment on the etymology and meaning of the word dievs 'god', he doesn't give it as an independent deity, although the word can be found in compounds Juras Dieve and Mezadievs. Maybe this topic was just too critical for him, as the same word is used for the christian God.