I love this piece of art as it shows the variation of hands that have been sketched. The effect of this in the format of a sketch book is that you can experiment in lots of different ways on one page to show the reader or the observer how many different techniques have been used to achieve the final piece.
When discussing truth, we often associate the truth about ourselves, which is often unknown. We gather truth through our senses, such as sight. A man of 70 may feel as young as he did 40 years ago, mentally, but his reflection reminds him of just how old he is. This image gives the impression of someone looking down at their hands, wrinkled and withered, they are reminded of their age and the life they've lead, reminded by the truth, despite how they feel inside.