nt of
doubt, and the verb should be in the subjunctive mood. _If_ (_as may or may
not be the case_) _he _be_ gone, I must follow him_.

s. 512. The use of the word _that_ in expressions like _I eat that I may
live_, &c., is a modification of the subjunctive construction, that is
conveniently called _potential_. It denotes that one act is done for the
sake of supplying the _power_ or opportunity for the performance of
another.

The most important point connected with the powers of _that_ is the
so-called _succession of tenses_.

s. 513. _The succession of tenses._--Whenever the conjunction _that_
expresses intention, and consequently connects two verbs, the second of
which takes place _after_ the first, the verbs in question must be in the
same tense.

I _do_ this _that_ I _may_ gain by it
I _did_ this _that_ I _might_ gain by it.

In the Greek language this is expressed by a difference of mood; the
subjunctive being the construction equivalent to _may_, the optative to
_might_. The Latin idiom coincides with the English.

A little consideration will show that this rule is absolute. For a man _to
be doing_ one action (in present time) in order that some other action may
_follow_ it (in past time) is to reverse the order of cause and effect. To
do anything in A.D. 1851, that something may result from it in 1850 is a
contradiction; and so it is to say _I _do_ this_ that _I _might_ gain by
it_.

The reasons against the converse construction are nearly, if not equally
cogent. To have done anything at any _previous_ time in order that a
_present_ effect may follow, is, _ipso facto_, to convert a past act into a
present one, or, to speak in the language of the grammarian, to convert an
aorist into a perfect. To say _I _did_ this_ that _I may gain by it_, is to
make, by the very effect of the expression, either _may_ equivalent to
_might_, or _did_ equivalent to _have done_.

_I _did_ this_ that _I _might_ gain_.
_I _have done_ this_ that _I _may_ gain_.

s. 514. _Disjunctives._--Disjunctives (_or_, _nor_) are of two sorts, real
and nominal.

_A king or queen always rules in England_. Here the disjunction is real;
_king_ or _queen_ being different names for different objects. In all
_real_ disjunctions the inference is, that if one out of two (or more)
individuals (or classes) do not perform a certain action, the other does.

_A sovereign or supreme ruler always rules in England_. Here the
disjunction is