Franklin compares a false friend to a shadow: both remain close when conditions are favourable, but disappear when circumstances become difficult. The sunshine represents prosperity, success or ease, while its absence represents adversity. A person who offers companionship only during good times may therefore be motivated more by convenience or advantage than by genuine attachment.

The contrast suggests that the strength of a friendship becomes clearest when it is tested. Difficult circumstances can reveal whether someone is prepared to offer support when there is little personal benefit in doing so. The quotation does not imply that every friendship must survive every hardship, but it distinguishes dependable loyalty from companionship that depends entirely on favourable conditions. Its central point is that presence during prosperity alone is not reliable evidence of friendship; constancy during adversity provides a stronger measure of commitment and trust.