What is the origin of the Minhag of kissing books as of Tehillim and other books? Should one kiss before or after?

Shalom, Thank you for your question. The custom of kissing printed holy books come from the much older custom to kiss the Torah scrolls (which obviously existed long before printing). This custom is mentioned in connection with getting an “aliyah” to read the Torah (see Mishna Brurah 139 (37) who writes that the custom is to kiss the Torah scroll before and after the reading. This is usually done by touching one’s tallit to the scroll and then kissing the tallit). The Rema (149) also mentions the practice of bringing young children to the Torah scroll to kiss it. It is written in the name of the Ari z”l that he would kiss the Torah with his lips, and not just via his hands or a tallit. Based on this, the Kaf HaChaim (155,12) writes that the correct thing to do is to kiss a printed holy book when opening and closing it, and that this helps one remember what they learned. In practice it seems that people today generally kiss the books when they close them – it is less common to see people kissing books when they open them. However, it is worthwhile pointing out a few things. Firstly, this is only a custom, and certainly not an obligation. It should be a sign of respect and love for the holy books, and the Torah within them. So, one shouldn’t feel that this is a law (halacha) - and certainly there are no hard and fast rules and regulations in relation to this practice. Next, Rabbi Yosef Eliyahu Henkin (Edus Le-Yisrael, #63) (one of the great Rabbis of the 20th century, in America) writes admiringly of the practice he witnessed among Georgian Jews who do not kiss a Sefer Torah directly, but who point at it from a distance and then kiss their hands. Aside from finding this practice to be spiritually appropriate, as it shows an awe of keeping distance from the Torah, he writes that it is good not to kiss a Torah adding “that they soil the Torah’s cover with saliva when they kiss it, and aside from this being degrading to the Torah, it is unacceptable from the perspective of health, and so too with kissing a mezuzah”. Let us add that in days of the corona virus this is all the more important. Of course, with one’s private and personal books, this might be less of a problem – but certainly applies to a synagogue siddur or chumash. Blessings.