Test tubes are used for very different purposes in the laboratory. For example, reactions can be tested or small quantities of liquid can be stored in them and they are suitable for heating over a Bunsen burner, etc. A test tube is therefore - as I understand it as a layman - a test environment in which either presumptions can be verified and proven or new things can be tested in very small quantities. As far as I know, however, there is no test tube that is designed in such a way that it can be placed upright because it is round and therefore cannot stand upright. The round shape has the advantage that it is more stable than a rectangular shape and allows the test substances to be distributed more evenly. A holder is therefore required. This simple example shows me that, for all the greatness of such a jar, it is useless without a higher support. I think this also applies to our lives.
I wish you an extraordinary day!
