[1] The essive case on a noun can express it as a definite period of time during which something happens or during which a continuous action was completed.
[2] Some fixed expressions retain the essive in its ancient locative meaning, however: "at home" is kotona.
If the inessive were used, kodissani, it would distinguish the activity from reading the papers, such as in the garage or in the garden (of the home).
The essive case is also used in a temporal sense with certain nouns, notably the names of weekdays, and vuosi (year), aamu (morning), ilta (evening), and yö (night), as well as dates.
[3] That can be seen in the following example: The example above illustrates the process by which marking of the essive case can be seen as creating two differing "worlds": one real and one illusionary.