The abstract timeline:
-------------------I----------------->
..... past .... present ..... future
Space is tangible. Time has historic direction (not spatial) and sense from the past to future. The future is historic in potency. An abstract line is required to represent the intangible time to be intelligible.
If space had one dimension beings would be lines and points. They would know the forward-backward (and viceversa), but not the up-down or left-right. In the time we know the beginning-end, but not the end-beginning. The natural sense of time is of the clock hands. Time is the dimension of becoming, not space.
Seven problems related with time:
(The choice of the Philochrony is in blue.)
1- real or illusion
2- reversible or irreversible
3- dimensional or dimensionless
4- objective or subjective
5- independent or spatial
6- tangible or intangible
7- intelligible or unintelligible